Honestly the things outlined here and addressed in the FEP is going to introduce a bluesky-like data portability to the fediverse;
You can dictate the domain and URL that your identity (a small document saying important critical elements) is hosted at, and migrate that.
You can dictate where your DATA lives, on your own storage provider, or at an instance, and migrate that easily as well.
If this is true, it'd fix many of the problems that migration currently has on fedi, and allows a true continuous identity and post history to exist. It'd require a refactor of many many many different fedi softwares, but imo it is worth it, since it transforms fedi into something else.