I'm not so concerned. Because it will remain binary compatible, people will be able to choose which language version to use on a library-by-library basis (as is the case today). So it's a lot different from, say, trying to mix two versions of Python. As long as the APIs remain presentable in both forks, it may end up being fairly transparent to the end user.

Merge compatibility is an even bigger bonus, as it should actually help push along the Typesafe compiler, in parallel with the feature roadmap Typesafe is focusing on, because we'll be able to see innovations actually working in production to prove them out.

The only big question mark to me is what this foundation will look like, and whether it can meaningfully contribute to the ecosysytem.