Someone should create a (dynamic) DNS provider (ideally a non-profit) whose only stated mission is to help people take ownership of their Fediverse, e-mail and XMPP identities.
If my identity were herrabre.mastodon.xyz (a subdomain instead of user-@), I could move to another instance by requesting a DNS record change, and my social graph would remain intact.
A trustable social contract would be needed so I kept effective ownership of the subdomain; the non-profit would be responsible for that.
Generalistic and moderated instance. All opinions are welcome, but hate speeches are prohibited. Users who don't respect rules will be silenced or suspended, depending on the violation severity.