It's really just a matter of someone caring. I don't see finding myself with enough time to work on that any time soon, but if someone has a good use case for it and motivation to get it done I'm sure it'll happen (and I'll gladly help).

Some things are dodgier - e.g. though supporting the AMX CPU extensions is quite viable in a kernel fork, I'm not sure if that kind of thing would fly upstream. Same with security features like SPRR - not likely to happen. But these aren't really things the average end user has to care about; they're bonus features, not anything core.