Perkin
I'm not really sure that an airline would be able (or willing) to take any action after the event.
If you find yourself in the same situation again I believe the correct course of action would be to immediately contact the CC who would take appropriate action to ensure that said passengers turned off their MP3 players and , especially, their mobile telephones. If they were unable to ensure this they would contact the Captain, inform him of the situation and he would then decide the next course of action. If this were to happen the passengers in question would almost certainly be met by the Police on arrival and arrested.
As for their ,less than civilised, behaviour towards yourself I would think the airline wouldn't take any action against them unless one of the crew also heard the abuse, even then they would probably just give them a warning to begin with. Sometimes we do come across people who are clearly moronic and possess the manners of a gutter rat and in normal circumstances, when they aren't endangering your safety, they are just best ignored.