What happens to user profile if I unjoin a PC from a domain?

We have a SBS server going EOL.  We only have some of our PC's on the domain already, and are considering doing away with the domain completely. (Most of our production runs on linux anyway).  I'm not sure what would happen with the user profiles if the PC's are unjoined from the domain though?  Can/will the profile just be converted to a local user profile with the same credentials instead of domain user profile?   Or does a whole new local profile need to be made and any settings/files/etc carried over manually?