It'll affect me for sure, pretty nuch no matter how restricted the activation is. Assuming we can equip actives relatively freely I don't really care that much how long I have to wait to get certain niche utility actives for a stall team. Stall teams will love this almost no matter what.
If it is as it was described before, (which, as far as I understand it, means that you lose access to one active once the other one is charged) do you really want to have to take the extra turns just to be able to use your not-niche active? I mean, sure, you
can stall the extra turns, but by then the situation might have changed drastically, or maybe you'll lose your cookie-cutter active in a situation where you really, really want it, and even if that doesn't happen, it's still extra turns you had to stall that you otherwise would not need to.
Plus, don't stall teams have a lot of crucial actives to stop themselves from dying? Losing even one of them can be pretty deadly as far as I know, and you can't even put Freezing Shift on a better leader than Beyzul because of horrible cooldowns.
Of course, we don't have details of how it's going to work right now, but it feels like that, unless it's a dual-active system, it will just be far too restrictive even for stall teams, let alone the infinitely-more-common spike teams, most of which can already clear 90% of the game's content without the system, so it basically becomes "unncessary extra that may actually fuck you over in the long run."
And that's not even getting into possible requirements and costs to actually equip the abilities themselves, or the fact that even if it becomes a relatively "no strings attached" system, they may just design new dungeons expecting everyone to have the system completely "solved". I mean, this is yamap we're talking about, he sure as hell loves his whales.
There's just so many possible pitfalls concerning this system, so yes, I'm skeptical as all hell. Either it will open up the doors to even faster powercreep (because it wasn't fast enough already) or it will be so cumbersome to use that most people won't even bother and it basically becomes dead on arrival.
And then there's option 3, where the system is 100% cumbersome and they still fully expect you to use it and do further dungeon design with that in mind. Which is the worst-case scenario.
So yes, I'm skeptical as shit.