The 747 is the only Boeing model that has never been stretched, until now. The A380 is too expensive for many airlines, and at the moment limited to only a few airports that can accept it. I am not putting down the A380, which may turn out to be an excellent machine in time, but it hasn't had an order in quite a while. So, Boeing have already 34 orders and no doubt many potential buyers queuing up; good luck to them I say.