I'm going to make a new version of this thread, since it's been a few years, and a lot has happened since that thread and I don't don't have the energy to necro that.
To refresh on what I have heard on what has happened since:
Elon buys Twitter, Tumblr reallows erotic (but not pornographic) content, some flocked to Mastodon (including yours truly, and newTumbl unexpectedly shut down after 4 or 5 years or being a repository of content banned from Tumblr. Even though I post on it sparsely when not using Postybirb, it's still a shame that newTumbl's gone.
There are still Tumblr alternatives that fill the role of a repository of pornographic content like Pillowfort, and the other alternatives like reblogme and Bdsmlr (which I have an account).
On the subject of the Tumblr alternatives, how is Pillowfort doing now, and with the shutdown of newTumbl, how are reblogme and Bdsml doing? And on the subject of Mastodon, is there a Fediverse version of Tumblr?