I've only played a little with MUDs, but I believe they are due to a big comeback as AIs like GPT-3 gets cheaper and more convenient to use. The possibilities for human vs AI interaction and also worldbuilding are endless.
I don't know about a mud comeback per se but I think this comment is very on point. There even was a mud (Written Realms I think?) that got into the GPT-3 beta. They have some interesting blogs on their experience.