Depends on the failure rate of the AoA indicators, but this seems like a reasonable question based on the current rate of failure. At least 2 failed in ~10,000 flights, so you'd expect simultaneous unrelated [0] failure roughly every 10,000,000 flights. There are 100,000 scheduled flights a day worldwide, so that's 3 catastrophic crashes a year if those were all 737s.

That seems a bit too high for comfort, but if they got another order of magnitude of reliability on the AoA sensor it would be OK. Alternatively, they can reduce the incident severity so that everyone doesn't die when the sensors fail.

[0] If there are multiple related failures, on the other hand, adding redundant sensors doesn't fix that.