Listen, NOBODY should be nerfed! Im getting tired of NRS scene always screaming nerfs when the devs need to start the habit of buffing lower tier characters to catch up to the good ones. Sub does not need any nerfs whatsoever. If anything, i would buff his damage output a bit.
Nerfs are for unintended gameplay. It's not just about character 'levels' in a tier list -- that's what people think about when they're new to this. The devs are thinking about if a given character/mechanic plays the way they want it to, or if something is being abused in a way that doesn't jive with their vision of the meta. And when things are found that significantly distort risk/reward or otherwise have (negative) unintended effects on gameplay, they get nerfed.
Not every nerf is about moving a character up/down a tier list.. Often it's for the sake of a game as a whole. People need to learn to think less linearly about these things.
The real key as far as viability is concerned, imo, is that if you take away a mechanic that is key to a character's gameplay for the aforementioned reasons, you just make sure that there's something else to balance it out.
In either case, it's too early, but it's time to level up our thinking about game balance changes.