While I don't have any ideas for skills I think a cestus or something like that would be good, we already have some unarmed combat animations, so making a few more of some punches and kicks can't hurt too much, along with the cosmetic option to hide the weapon if you want to.

Another idea I had being magic spells, the weapons themselves might be gloves or rings and bracelets. It would kind of be like the staves but there would be a trade off, maybe less range but more power? This could open up the option of using two magic elements at once by dual wielding spells or using a 2H variant that resembles the dual casting perk from Skyrim. I see plenty of potential for synergies and maybe even more magic skills because I feel like 2 staff skill lines aren't enough when there are more non-magic weapon skill lines, trying to even things out a little more should make things more enjoyable.

It's not going to happen. I don't believe they have the personnel or wherewithal to add features like that with out them being half baked or buggy.

Can happen. They keep adding zones and features every year.
Psijic Order.
Scribing.
Antiquities and Scrying.
No difference if they were to add a new weapon.
If the game is too old, then tell me how they added Summerset, High Isle, and West Weald.
If it's too old to add a weapon and skill tree, it's too old to add more zones and skill trees.
If they can add more zones and skill trees, surely they can add more weapons and skill trees.

woah there.

Why add fancy new stuff when there's some basic changes they could make far more easily that would do far more good.
(i.e. this is what they're already doing and it needs to slow down).

Rather:
Separate destro staves into separate skill lines + add new "magicka" tanking weapon so that ice staves don't have to cover two roles.