Since it's basically all anecdotal, I'll say my gazing-into-the-crystal-ball educated-guess feeling that Python 4 will make the entirety of Python about as popular as Perl is today if: it doesn't get rid of GIL and at the same time implement a JIT compiler, and at the same time remain 100% .py source-code compatible with Python 3. The developers have dug themselves into this mess with frivolous differences ("print" a…
If you see only print, you are missing the point.
But good news, there are many projects working to improve the perfs and/or bypass the GIL this year.