If I could boot up Python with --no-gil I might give it a shot but it looks like a hassle to install a no-GIL Python now. And after all that hassle I'd expect it to take years for the details to get worked out.

One reason Java was successful with thread safety was its xenophobia. Sure you can load libs with JNI but it feels like putting your hand in a toilet. If you add threads to POSIX you will always have old libraries not built with threads in mind, if you start out with threads the whole ecosystem is built on the assumption it should work right with threads.