As we have discussed in this forum before: That ain't gonna happen no time soon. I consider that, if one carrier did enforce the rules, many pax would abandon that carrier. They see the carry on as a 'free' and expectected part of the ticket price'. Other carriers would benefit and see that they ought not to follow. If it were possible for ALL carriers to enforce ALL the rules ALL the time ... well we would see Capt Danny's Pig overtake him in the cruise!!
Do not know about enforcement, but Swiss just slashed the piece allowance from 10 kg to 8 kg.