I think this is the answer.
Lemmy and (maybe) Mastodon (I don't know enough about it) will be the inspiration for something that goes mainstream - but I do think that they'll be the Myspace to the next big things Facebook - Perfect for people who know how to take advantage of it and it will be a mild success because of it; but someone will come along, streamline and spruce it up and that will be the new standard
Psyren, Double Arts and if we're including "Indefinite Hiatus" then Iris Zero are all ones I go back to every now and then and think "What If?"