If Ukraine just completely collapses like Afghanistan once the West pulls support, yeah maybe (although more likely adding Dnepropetrovsk and Kharkov for the full Novorossiya).
But I’m leaning more towards Russia just keeping what they already annexed to break the stalemate.
These things go slowly, slowly then all at once. There's been a lot more movement on the front these last few months, and the Ukrainian army is pretty depleted. At some point Russia is going to wind up for a big kick at an open door and we'll see things starting to look more like Afghanistan in 2021 or the final months of the Third Reich. A negotiated peace is the only thing that can prevent this kind of outcome, and Ukraine might be smart enough to go in for it before things really start to deteriorate. Even so it's hard to imagine the Russians crossing back over the Dnieper and even harder imagining them taking a defended Odessa. If they get Odessa it will be in a peace treaty, not by military force.