It continues to expand because there's nothing else like it: a language and editor agnostic tool for implementing parsers for IDEs. All of the editors come up with all kinds of niche hacks and DSLs. All editors keep reimplementing broken, partial, regexp soups..

I can only see more editors just giving up on this and going all in of treesitter.

It's not only neovim, btw, the next emacs is also gonna have it included.