'If an airline can save a little by buying the A380 over the 747ADV but they have an all Boeing fleet, would they add the Airbus and all the costs that come along or just use the Boeing? I think that most would use the Boeing and that is what Boeing is trying to figure out right now!
At the moment airlines have the choice of a 744 ('80/90's technology/efficiency) which B can heavily discount (all R&D and associated costs amortised) or A38.
If B develop a 744ADV, they can make a few changes that produce the easiest (cheapest benefits), like new engines, tweak wing, lighten structure. It will produce benefits over the 744, but cost more than a 744, and be a short life (interim) improvement for customers, with high degree of commonality. It could be ready in 2008/9. But who wants it? Quite frankly this version of the 747ADV could be a retrofit to existing aircraft, something no doubt that B are concerned about. Conversions occur instead of new sales.
The other option is a much more drastic change. This version of the 747ADV would offer A38 operating efficiencies, or better. Delivery in 2010/11, depending how much of a new model it really is.
But if B are delivering a 747ADV in 2011 (with no R&D/production & start-up costs amortised), and A are delivering A38's (with a high % of R&D/production start-up costs amortised), A has the ability to discount (just as B can do now with the 744), where B won't be able to.
That shifts lifetime ownership costs in favour of the A38, and allows SQ
for instance to operate one model instead of 2 (immediate savings), and the financial penalty of operating a 550 seat aircraft with 450 passengers, versus a 450 seat aircraft with 450 passengers shrinks.
B are now trying to gain support for something between these two extremes, with little interest. I haven't encountered a single client that is seriously looking at the 747ADV, or believes B is serious either. The one qualification is, if A38 performance isn't as expected. If this happens, the expectation is that sales of both the A38 and 787 will halt, pending A38 solutions and 787 performance.
UAL you mention a 'Boeing fleet'. Are we talking 747ADV commonality with other 747's? Apart from the B name, the current model range is anything but common. The 747ADV design team (or perhaps other more senior influences)can't even decide whether cockpit commonality will be based on 744, 777, 787 or something else.