Technically, they all fall under those rules in places like the EU already, those rules just aren't being enforced.
Long-term, the Fediverse isn't a social media platform, the instances are platforms, and they just connect to each other. I'd only expect enforcement on the few instances that are "large", like a million users in size or more.
If instances choose to comply, either by capping users or shutting down, it could be good for decentralization of the network.