How about:
-Insure the pax cabin bags so in case they leave them during an evac they get a compensation. EXPLAIN this to pax.
-During an emergency cabin prep before landing allow the pax to take small personal items from the bag. Such as passport, cellphone, wallet, etc.
-After that, before landing lock the hatracks and put some sticker on each lock clearly stating it's not gotta open.
-The safety demo has to be more explicit somehow. I have no idea how, but the relaxing music and smooth videos of most airlines just don't get the pax's attention.
About arrests and prison, I don't imagine how you can convict some Indian dude that saw a plane for the first time in his life, doesn't know how to read and has no idea of what the hell just happened... Locking him away is not gotta solve much I think. Plus in any European court the pax could simply state that he\she was under a lot of stress (and it's true) and couldn't think straight under those circumstance, so the pax simply grabbed the bag without realizing what he was doing. This would be enough to get away with it.