I really hope the folks who haven't migrated over here from there will when it goes dark. I think if any community could, it's technical communities like the KDE community.
Yes for sure I'm hoping at least technical comunities do a mass-migration
There's already some with a bit of traction
If Lemmy stays as it is, it won't work. The two largest Lemmy instances seem to be Lemmy.world and Lemmy.ml. I've been able to sign up on Lemmy.world and Feddit.nl (because it's local to me), but not on Lemmy.ml, where the KDE community actually is, because my sign-up still has to be approved (no e-mail with more information or anything.). So first, I have to use the KDE community at Lemmy.ml through another instance and second, my subscription to the KDE community has been pending for days now. Third, it's entirely possible to have 2-3-4-5 KDE communities scattered over multiple instances, but they are all "Lemmy".
"Normal" people are never going to use this. It's way too complicated for them, and federation is too slow if the community you want to subscribe to is on a slow or overloaded instance.
I mean with federation it shouldn't matter which instance people sign up on. I think largely they should pick smaller ones which might be local to them, or they know their admins, or based on the admin's rules and approach to running an instance. The "subscription pending" thing is actually a Lemmy UI bug, you should actually be subscribed despite the UI, I think it's this bug report which covers it.
Federation works based on a push model where new posts are pushed to the servers it federates with, so the speed will largely depend on the local instance, which should be caching the posts and comments, not the remote instance.
KDE is an international technology team creating user-friendly free and open source software for desktop and portable computing. KDE's software runs on GNU/Linux, BSD and other operating systems, including Windows.