Matthew Perry is struggling with addiction. I mean it's nothing new, it was already ongoing and apparent during the show itself. You could see it on the show, his extreme weight loss and gain during seasons 3 and forward.
By the way, Courteney Cox looks so much better than few years ago.
I think this is the only solution. Would it really be good, a new scripted episode with old characrters? Especially that some of the actors are struggeling with drugs and other stuff? That would be a very sad episode.