They'll be able to. Stop bellyaching. Anyone can spin up their own lemmy or mastodon instance and federate it with meta if they want, or they can just join any existing instance that federates with meta.
That's the wonderful thing about federation: if you don't agree with the choices made by the people running your instance, there's plenty of other instances to choose from! Most instances will still have access to all the same content, so it's not like telling someone to just leave an entire social media platform.