The upcoming change to how shadowy disguise fundamentally works (10 years into the game, no less), doesn't bring anything of value into the NB toolkit, while removing one of the class' best defensive capabilities.
In order to use the new skill for extensive invisibility, you have to have a build geared heavily on magicka sustain (including replacing all damage enchantments for regen), while also slotting leeching strikes to counteract the drain (and leeching strikes costs health, which another issue, as I'll explain below). This means that a) your build won't be effective for anything else, b) you have to make space on your bar for leeching strikes.
However, we can already achieve near permanent invisibility in the game, using either a speedy build on a stage IV vampire, or a Darloc Bare/Torc of tonal constancy build (among others, but these are the two I have used), and for these we didn't have to slot any extra skill on the bar and sacrifice slots, not to mention they are available to all classes as well. With the new cloak you will need a specialized build
and two skills for perma-invisibility, so it doesn't bring anything new to the table, and it's worse than what we already have.
Now for the things the new change removes: when you want to sneak to escape on a NB, you cloak and then you sneak (2 button pushes), now you will have to untoggle the skill, because the drain is insane (so 3 button pushes, and it's clanky, so the longer it goes on, the worse the drain). If you want to keep using cloak in a high pressure situation, you have to build heavily into mag sustain, like I said, and spam leeching strikes as well, thus burning your health, and risking being left with lowered health if/when you get revealed. You just won't be able to use the skill effectively, and the only other avenue is to re-morpth it, which means an entire different playstyle that a lot of people don't enjoy.
No one ever complained about needing more invisibility in the game, no one ever complained about having to recast cloak,
and no one likes toggles in fast gameplay like PvPiing, so why is the skill changing? Just to remove NBs defensive abilities? The skill itself is not problematic, it's in combination with all the proc sets that make it dangerous. If you are set on nerfing it, then just ramp up the cost: this is will still limit the usage of the skill, but it won't make the
actual use of the skill harder, which is the case with the toggle.
@ZOS_BrianWheeler