Maybe it can happen now among the apps that have put their foot down about a complete end, but certainly loses a lot of momentum from those who might have already uninstalled them.
And in theory not even that. As long as the traffic can be redirected to a different server it should still work. In practice, however, at least Apollo has some server-side components so it wouldn't be totally plug-and-play without developer support.
Sadly, I'm not sure how to get in touch with the developers/users who may be interested.
(I've also heard that someone's working on a Reddit/Lemmy gateway, but I don't know who they are or how far they've gotten.)