I don’t think that’s ever going to be in the plan, because the issue with Nouveau was the older cards, or more specifically, that the code was based on older architecture.
NVK was able to utilize newer code from the newer RTX cards to get a more performant base to build upon (or at least, that’s my understanding). Even if they wanted to, I don’t think they can actually go back.
The issue actually is them being unable to control the older cards power state due to Nvidia being dicks (as always). That’s the only thing stopping them because it’s a shitload of work to reverse engineer Nvidia’s fuckery (Nvidia REALLY put a lot of effort into it to make it very hard to actually do)