I would certainly like to see a replacement and Mastodon is deserving in many ways - pretty mature, built with sincere motives of delivering a better communication platform/protocol, decent UX and maintainers that listen. To the extent I express pessimism about it, it's because of patterns of social behavior rather than any shortcoming of Mastodon itself. Overcoming network effects needs some kind of can't-live-without-it innovation and sadly 5 years of trying demonstrate that federation alone ain't it.