Software update is only part of the issue.

737Max has left and right Angle of attack sensors (I have read that A320 has three AOA sensors). If one gives and erroneous reading, the MCAS defaults to it where with A320, with one erroneous reading it checks with the other two and goes with the two that agree. By the way two sensors is inherently STUPID! How do you know which one is giving the "erroneous" reading? This is clearly a design flaw leading to a single point failure mode with MCAS software.

To completely solve the issue (erroneous AOA input), Boeing needs to go to three AOA sensors and modify the software to demand elimination of the outlier seniors input.