My hunch is that even calling it an "overhaul" is too strong of a word. I think what we'll get at this point are mostly quality of life adjustments.
In that spirit, I'm optimistic that in particular they'll address some of the game's defensive options that get abused to steal an unfair attack advantage. These are some of the most demoralizing, "why tf do I play this game?" things that shouldn't have stood for as long as they have.
The wakeup system. Everyone hates it, because it's so OP it literally rewards the person who made a mistake and got knocked down. The new animation that visually signals delayed wakeup is a good start, but I'm hoping they've cut some of the options (e.g., only one delayed wakeup timing) or at least made them more expensive (e.g., forward roll to cost one offensive and one defensive bar).
Breakaway. Everyone agrees it's terrible. It's not going away at this point, but NRS needs to do something to guarantee that the defender never, ever gets to combo the attacker after breaking away. Doesn't need to be a complicated change: just force the defender to stay in a knockdown state until the attacker returns to neutral.
Fatal blows. Lots of debate on this topic, but I think everyone agrees full-screen FBs are toxic and shouldn't be a thing. They're not going to change FB animations at this point, but at least make full-screen FBs (e.g., Erron, Kabal, Geras, Cetrion, Noob) a lot slower. Even better would be if FBs had a lower activation point (from 30% to 25 or even 20%) and can only be attempted once a round.
Kombat League wifi filter. Yeah, yeah, I know we won't actually get this, but I can dream, right?
Other than stuff like that, I don't think we're going to see changes that would completely disrupt the meta. I don't see them increasing plus frames on everyone's pokes, making hop attacks launch for a combo, anything like that. That would create chaos and require completely re-balancing the characters all over again, and I don't think they want to do that. I could be wrong though... we'll see.