The idea of migration and data preservation has been a topic since day one, since that's a big reason why so many moved to the Fediverse. I still haven't seen a perfect solution, and maybe there isn't one. Perhaps just having a lot of redundancy (oh no, reposts!) is the only true way of protecting posts for as long as possible, and even then...
Ernest started things rolling with something that probably wasn't ready for the demand, but it was there when the time came. That others forked off from it and kept it going is the bright spot here. I appreciate Lemmy and even have an account from the first days, but I like the kbin/mbin setup better so that's where I sit.