> In my opinion, Python needs to have an urgent answer to the use of multiple cores.

Subinterpreters are an answer (heck, so is multiprocessing).

Whether between them they are enough for Python's domains is another question. Probably not for the long term, but possibly for the neart term. But anything more is going to be a big lift, no-GIL is the obvious broader answer, so its good its being worked on, because by the time its betond question that its needed, it’ll be too late to start working in earnest.