THOUGHTS ON A POSSIBLE FIX
On the subject of a 'software fix', as well as possibly feeding data from both AoA sensors to the microprocessor concurrently rather than consecutively, would adding another precondition to MCAS operation affect certification?
What I am suggesting is a >minimum altitude to be achieved before operation of the system.
The stabiliser is a very powerful control surface and having a system which can repeatedly trim the nose down at an altitude where time to recover is limited has the potential to cause more harm than it can prevent. A system which can require both pilots to simultaneously apply greater than normal elevator control added to the need for either the system to be disabled (one hand off the control column to operate two guarded switches or selection of flaps), opposing the MCAS trim by repeated manual trim control, or all three is quite frankly an ergonomic mess!
Despite the 'it wouldn't happen in a Western/white airline' nonsense we keep hearing, as many people on here have said, MCAS operates normally most of the time and even the best forewarned crew would (and should) not immediately respond to every upset as though it was an MCAS problem. Even a very quick and efficient diagnosis of the problem could still take the same length of time as it takes for the automatics to put your aircraft in a potentially fatal nose down trim. This is not primarily a training issue, it is a systems issue which Boeing now seems to be accepting despite the 'making a very safe aircraft even safer' statement.
This is a general observation, regardless of the cause of this particular incident. As mentioned above, the best time to have an AoA sensor failure is just after take off (even at night) when there are still some visual references to help you decide whether to believe either what your instruments are telling you or what you are seeing outside the cockpit.
So if we don't get a rethink of the whole system, would putting a minimum altitude requirement for its operation pass existing certification or is MCAS protection required for all phases of clean flight? As MCAS is intended to provide protection in low energy situations a great deal of thought would need to be given to how the minimum operating altitude would be determined.