I know it's pretty early for this one, but there is no reason not to start early with the feedback.

First of all I want to highlight what I think is already good about the Necromancer and then I want to get into some of the points I think should be improved. This will by no means be an exhaustive list, so feel free to comment your own thoughts down below what you like about Necromancer and what you want to see improved.

Here we go.
What I like about Necromancer:

• I like the fire-and-forget approach to Necromancy. Micromanaging pets feels bad so Necromancer not having to deal with that is great. It's also fits the TES lore aspects of Necromancy not being a permanent affair - at least not without considerable prior preparations, which a Necromancer in a lair has, but a wandering Necromancer doesn't. Which brings me to my next point...
• I like how the corpse mechanic creates a strong identity around standing your ground or creating danger zones that your enemies have to avoid. That puts them naturally at odds with Templars, who also like to stand their ground, which is kind of perfect thematically. I'm not necessarily a fan of the implementation of the corpse mechanic in every single case, but there absolutely is strong identity and theme here.
• I like the healing options for Necromancer. Having a ghostly healer, a tether that heals everyone between you and the corpse as well as everyone around you (Braided Tether) is neat. The Reanimate Ultimate has its issues, but when you do make the decision to slot it and you do get to use it, it can quite literally turn a lost fight into one that can still be turned. There aren't many moments in this game that feel better than or as good as that. When talking about class identity, from a design perspective, we should ask ourselves what are these classes' hero moments? For the Necromancer healer that is their hero moment. It's moments like these that spark joy and make you feel good about having brought a Necromancer, because only a Necromancer could have done what you just did.
• The skills in Grave Lord are all awesome, maybe except for Shocking Siphon. Other than updating the visuals and the "feel", I wouldn't actually change much in that skill line. Just the numbers, probably the passives. Throwing a burning skull at your opponent is such a simple but cool thing to do that we kind of take for granted. It's just a shame the skill still doesn't feel as good to use as something like Force Shock from destruction staff.
• Scythe and Bone Armor are also great skills in terms of theme and power. Bone Armor has a bit of a short duration in my opinion, but the recent change to have it grant you a corpse upon cast, that you can even use out of combat to prepare feels grea and has turned the skill from "kind of bad" to "kind of great" in my opinion. The Bone Goliath is also cool as a concept, but it has its issues.

What I dislike about Necromancer:

• With Major Vulnerability becoming a mainstream debuff effect that plenty of sets in this game can provide, Necromancer has pretty much lost its raison d'être - it's reason for being. Before you'd invite a Necro to any raid just to get that debuff. That was good, because it meant that even when Necromancer was in a bad spot balance wise, they'd still be allowed to join. None of the other classes lost theirs. If Major Vulnerability hadn't been put on so many sets, even the Arcanist meta in PvE would not have been able to get all Necros kicked from the group. So with it being gone, what's the point? The Revive ultimate never has to be used in ideal conditions, so that's not a reason for good groups to bring a Necro. That's a crutch, only useful to groups that are still learning. If we can't make Major Vulnerability uniquely Necro again, we need to give them something else.
• Too many tethers. Braided Tether is fine, because it's also an AOE around you. And Detonating Siphon has its uses when you are using Corpse Burster for example. But Mystic Siphon and Mortal Coil are pretty much identical skills, with one for damage and the other for healing, but neither really feels great or unique. I would turn Braided Tether into the base functionality of the healing skill and come up with better morph choices, while I think Shocking Siphon needs to be replaced with something else entirely. Perhaps a skill that turns a corpse into a bomb to keep the fun part of Detonating Siphon alive and to double-dip with Corpse Burster for some fun interaction.
• As mentioned earlier Flaming Skull does not feel great to use. It was improved recently, yes, but there are still issues with weaving. Until those are resolved, and the use case over Force Shock or Snipe is made more clear, I won't see myself using this spammable.
• Sacrificial Blastbones. That ability makes no sense. You expend power to animate a skeleton so the skeleton can... die again? Where are you gaining that power from exactly? This skill has the functionality of a corpse consuming ability, not a corpse generating ability. Actually, why not put this on the other morph of the corpse detonator ability I described above? It can't be that hard to take Blighted Blastbones and give it a different coat of paint with a different secondary effect and make it cost magicka. That's what we've had and I think that's what we want back. Especially if we move the empowering ability over onto what became of Shocking Siphon.
• The damage over time theme. I feel like Necro has a bit of a split personality here. I explained what I dislike about Shocking Siphon earlier but other than Boneyard, it's also the only damage over time ability in the Necro's kit despite the class supposedly being more focused on it. Necro actually seems to be quite the burst oriented class. That isn't to say that it doesn't make sense for Necromancers to get a bonus to damage over time effects. It's very thematic for a Necro to afflict the enemy with lots of damage over time effects and debuffs that eventually overwhelm the enemy in a battle of attrition, but the classes kit is just nothing like that. I think we can work with status effects some more, especially considering how diverse the damage palette of the Necro already is, so why not lean into that more? Maybe take inspiration from sets like Serpent's Disdain or Xanmeer Spellweaver (or both) to give Necros a boost that everyone will appreciate with the option of building fully around it if you so choose.
• I already mentioned Bone Goliath, but I feel the entire Bone Tyrant skill line needs work. Bone Goliath is kind of weak and not all that useful. Sure it can save your life for a few seconds, but it's also not doing much else. At least Vampire ult and Corrosive Armor deal more damage and heal more, with DKs also get their resources restored thanks to their passive. By comparison Ravenous Goliath is just sad. Meanwhile Pummeling Goliath is pretty much only relevant for Bash Builds and Bash Builds cause lag, which is very sad. For a playstyle that's already so obnoxious due to the lag it causes even in duels and the ability to go all in on resistances while being rewarded with increased damage, I don't think we need to then also give them AOE damage. Enough about Goliath though. Grave Grasp still misses the mark. Get it? Because that ability is difficult to land and easy to miss! Why not make it a targetted cast that then immobilizes in an aoe around the target? Bone Totem is also a bit meh. Sure, it's more useful than Grave Grasp, but not exactly cool either. I think we could make this ability generate a corpse and turn Remote Totem into another summon because the tank Necro doesn't have any summons which feels unfortunate. Maybe a ghost that's chasing your enemy to fear them, or a skeleton with a shield that protects allies?
• Finally the pet/corpse limit is just a very sad thing to have. I understand that it was implemented for performance reasons, but I think this is taking things too far. There has to be a better solution than 5 pets/corpses.

Wishlist and more ideas:
While I was playing Infinite Archive I got the Necromantic transformation and thought to myself, why can't Necros get something as cool as this ability? So I thought why not let the revive ultimate be a little like the Lich synergy from infinite archive. You use it, it spawns very many temporary pets that swarm your enemy until they expire and leave corpses, regardless of whether somebody was revived (except you can't target them, to not make it an obnoxious bodyblocking mess) and cause your enemy to die by a thousand cuts, while still retaining the ability to revive up to 3 allies in the target area. That way nobody would feel bad for bringing this ultimate and the healer would be happy to use it, especially if the other morph could leave an area where it was cast that provides allies in it with a shield or strong heal over time so the ult can compete with Barrier.
The other idea was the Lich transformation as a more damage focused alternative to Goliath. Sure, Lichdom is usually a permanent affair, but let's handwave that away for the rule of cool, say the appearance is a dreadful illusion of what your Necromancer might become in the future, while temporarily empowered from whatever unholy ritual you just used (or perhaps this was your true form all along and your normal appearance is the illusion). Gameplay wise, something fun that's probably not balanced at all would be to have skills cost 0 magicka for the duration of the ultimate. Sounds busted, I know, but if we take away the extra health and replace it with extra max magicka (just for the damage/healing calculation) I can see that being neat. We increased the cost of skills like Time Stop to ridiculous 8k magicka because otherwise it would be too powerful. But ultimates should be powerful and would give you a somewhat brief window of being able to spam Time Stop before the duration runs out and you are left with a skill that's mostly unusable on your bar, making it somewhat fair... maybe?
Finally I think it's a Criminal Act from the developers that Necromancer have not even one single passive or active skill interacting with soul gems. I think we should incentivise Necros to use Soul Trap, maybe by having a passive triggering from using a soul magic skill, or from filling a soul gem. Or give them their own modified version of soul trap. I can understand why we wouldn't give Necromancer something that consumes a filled soul gem, since we don't want people to randomly run out of soulgems and realize they have to revive at a wayshrine, but especially on higher levels you end up with more soul gems than you'll ever need. You could even make reviving as a Necromancer cost no soul gem if that was the problem! Perhaps Shocking Siphon (since it's unlocked way down the line) or whichever ability has replaced it, could have a line that says if this ability was cast with no valid corpse in the area, it instead consumes a soul gem and is centered around you. Flavor-blast the Necro with extra soul gem utility!


Anyway, these are my ideas.
I was actually involved in hypothetical Necromancer class discussions back before Warden was even a thing and we all believed they couldn't/wouldn't turn an NPC/villain class into a playable class. So being here again and talking about design philosophy of the Necromancer is a bit nostalgic. I made some suggestions back then that turned out pretty close to what Necro ended up being - with in hindsight some admittedly very flawed ideas, like Necro having no self buffs and instead being debuff focused (which backfired, because potions exist and made Necros too strong at first and then in need of nerfs, resulting in them now having all of those buffs after the nerfs left them too weak). I hope my understanding of the game has improved since then.