I'll try to migrate Accounts but be prepared to be logged out again :((.

The new system will allow users to have multiple instance logins under one account - this will make it possible to seemlessly switch accounts when one or more instances go down.

Use case example:

You browse Nemmy with your lemmy.world account when suddenly lemmy.world goes down, then Nemmy can automatically switch you over to your synced lemmy.ml account, which has the same subscribed communities. Now you can continue browsing your feed, posting Posts and Comments - as if lemmy.world was still up.

Basically this is the next step of the instanceless featureset of Nemmy which takes over instance handling which is currently handled by the user.