I disagree, the 747-8 can be had on relatively short notice. It hasn't been selling well, and there is only a very small backlog. If UAL were to order the -8, I think we'd have planes before TK could spool up training and get a sim.
In general, the 400's have too much life left, (Not ours) and it is an expensive plane for a small increace in productivity/efficiency. Worth the investment? My opinion, yes. CO managers have something against the 747. I have no idea what. The Airbus A350 is a huge gamble, and with the stretched out/delayed deliveries, might not work for our timelines. Again, the -8's would.
777-300ER while a fantastic plane, can't haul the cargo, and deliveries are too far out with a big backlog. I do have a friend that sells new Boeing planes at Boeing, if Jeff wants, I can do the introductions.