Simplest thing would have been to remove MCAS. Since it's not done means MAX cannot fly without it. The software upgrade consist of reduced authority of MCAS so that stabilizer will never override the elevator authority and using redundancy toto disab it in case of a disagree. Now the question is will reduced authority MCAS do the job of preventing the stall for which it was installed? Two aircrafts were driven into ground and if the third one is stalled into ground how will it be treated? Secondly in case of disagree the disabled MCAS will it be land ASAP?