If it is possible, then I think it should work. I believe this might be the way they are planning to go, because someone mentioned about a separate partition.

Honestly, I think they should just relocate it to a different location that can be persisted and rebuild the packages. I don't think people care about the location as long as they don't have to recompile every single thing. This could also be useful to catch all bugs where /nix was assumed.