Lemmy/kbin and other reddit alternatives, I think they have a higher chance than mastodon, diaspora and other alternatives more focused on "web presence".
Reddit and Lemmy are about threads and posts, stuff that you're supposed to interact with hours, perhaps days, after the initial post, stuff that you're supposed to look for and find later on. Evergreen content
Twitter and Mastodon are about the "right now". Stuff from 3 days ago is a lot less likely to be interacted with, or stay relevant. It needs new content to be consumed on a daily basis, just like Pixelfed (fed insta) or Tiktok. I think that makes Mastodon less likely to remain relevant long term, but what do I know?