I've now encountered an issue I believe that PEP 533 was intended to address:

When an asynchronous context manager is created within an asynchronous generator, if the generator is not iterated fully, the context manager will not exit until the event loop cancels the task by raising a CancelledError, long after the context manager is assumed to be out of scope. Per PEP 525, I can call aclose coroutine method to cleanup the generator, but it requires the code iterating to be aware that that closing the generator is necessary. 

Any appetite for putting PEP 533 back on the table to address this issue?