Textmate style vs tree-sitter

Hello noob here.

short version:
Seems like atom is on its way to fully support tree-sitter for syntax highlighting, how much time can we expect textmate grammars support to still work?

long version I've been searching for an IDE that supports good syntax highlighting for both python and cython, notepad++ was fine for python but the lack of auto-indentation for cython is annoying.

Then I found atom and it has a language-cython package that suits my needs but it seems like atom is on process of replacement from textmate-style grammars to tree-sitter based ones, is it right?

There is no activity on language-cython's repository for a long time, I want to fork it and make a few tweaks but not if it’s going to stop working in the near future.

The manual is calling textmate grammars legacy and encouraging the creation of tree-sitter ones but I really dont feel like coming back to js and learning a whole new platform. So for how long can I rely on language-cython if no one is maintaining it?