But shouldn't old GIL python versions be fine running code that is no-GIL compatible (assuming it is otherwise compatible)? Having a thread per process doesn't

But shouldn't old GIL python versions be fine running code that is no-GIL compatible (assuming it is otherwise compatible)? Having a thread per process doesn't mean you cannot run code which is fine with having n threads per process. So if you maintain code which is otherwise compatible with e.g. python 3.6, after making it no-GIL compatible it should still be compatible to 3.6.