Just have Boeing execs and engineers fly in it for 100 hrs or so.
The stall profile of the 737/MAX model still exists, even with modifications to MCAS. The engines are too far forward. In an emergency, when a pilot gooses the engines, the aircraft will pitch up. A pilot's first response will always be to use the elevators (pushing forward on the control column). So, the next point of failure will be on overworked elevators. The next crash of a 737/MAX will be an elevator failure.