Well of course they will grab their hand luggage
This has been gone over time and time again here.
Modern passengers are not stupid
Their hand luggage contains their most expensive and valuable/hard to replace stuff: and they know the compensation limits
They are not risking the hand baggage being returned to them somewhat later but curiously 'missing' some stuff from inside it or with some stuff now mysteriously 'broken'.
.....and then they will have to argue the toss endlessly with some insurance company about exactly when this happened and probably loose out in the end.
So provided the plane is not disintegrating around them they are going to grab their stuff and run.