Bags on board
The implementation of locks would introduce a lot of extra weight, certification, extra SOPs and new procedures. It's a big rethink and redesign. I doubt this will happen in the next 10 or even 20 years.
The quick and simple solution is what Ryanair and Wizz did, but only partially. Stop people coming on board with huge bags. They only allow certain amount of tickets to be sold with onboard luggage.
If however, airlines would stop cashing in on these and ban massive bags on board it would certainly stop these unnecessary deaths.
However this will stop them selling priority and it's a massive cash cow.