Indeed. Data longevity is a concern for me in general. There have been enough Lemmy instances that have disappeared (including once I used to be on) that our ability to become a massive first-hand knowledge center (like Reddit) is endangered.
I know user portability is getting active attention. I'm hoping at some point there's a cohesive solution where all our data is in our own hands and we can plop it on to any instance of any service with a few simple steps.