> That might still be an option, all code before a license change falls under the license at that time.

This is technically true, but as more time passes, it will be more and more unlikely that someone is willing to fork an old codebase, especially since the newer version has so many bugs already fixed and the old version gets outdated in many aspects fast.

So if there is not any active fork right now that is backed by a community, then it's more likely that we would see alternatives coming up like the one OP mentioned here.