Actually, what needs to happen to stop the holding for heathrow is for the airlines to sit down and negotiate arrival times with each other, instead of all trying to pile in or depart at the same time to the same routes...
That is not going to happen though, as the reason they all want to get out to the same destinations at the same time and return from them at same time is because that is what Joe Public wants.
BAA are not going to put a stop to it because it may scare the airlines elsewhere... it's a no win situation I'm afraid