New articles will still reference tweets, as people and communities are still engaging on there. You can view an embedded tweet in an article, but you can’t read any of the replies to the tweet nor view the tweet as a whole.

My understanding is that using Plex/Jellyfin is perfectly fine. The only real concern would be the actual way that the media was obtained, but you can host whatever you want on Plex.

I kept googling questions and clicking on the reddit posts. Reddit seems to be the only place to get some real answers sometimes.