Doing full blown zero-copy ownership transfer of actual Python objects would be more difficult, since the current plan is to have separate memory allocation pools per interpreter to avoid excessive locking overhead, so I don't currently expect to see that any time soon, even if PEP 554 is accepted. Assuming that remains the case, I'd expect multiprocessing to remain the default choice for CPU bound use cases where all the interesting state is held in Python objects (if you're going to have to mess about with a separate heap of shared objects anyway, you may as well also enjoy the benefits of greater process isolation).