777-300LR's are the only real replacement for the 747's. Unless, of course, you consider codesharing as a replacement.
If they displace 1/4 of our 747 pilots next year (barring an early-out program) there will be a massive downward bid tempered only a little by the 330 deliveries. Any aircraft we order in October will take at least 2-3 years to materialize.
So we've got that going for us ...