KenV, I would suggest that if the USAF was to change tack, which clearly it won't, Airbus has sold quite a few of these Multi Role Tanker Transport aircraft and so the waiting time would be considerable. I am not aware of the KC46 receiving the same interest?
1. The RFP had hard delivery dates that lay
years in the future. BOTH manufacturers' proposals met those delivery dates.
2. If USAF were to change horses in mid stream at this late date, USAF would change to the KC-45 and
not the MRTT. Although KC-45 is based on the A330-200 like the MRTT, it is quite a bit different than the MRTT, just as the KC-46 is quite a but different than the KC-767 that Boeing had previously produced. It would take a few years for Airbus to develop the KC-45 just as it is taking Boeing a few years to develop the KC-46. The production slots would be reserved years in advance while Airbus completed development, so the wait for delivery would not be "considerable".
On the other hand the waiting time may be infinite. By the time Airbus developed the KC-45 from the A330-200, the A330-200 may no longer be in production. The production line may have converted over to producing A330NEOs. Boeing's replacement for the 767 is the 787. Those are entirely separate production lines so Boeing can produce KC-46s at the same time as 787s. I don't know, but I believe that the A330 production line will be converted to producing A330NEOs. So the only way to produce KC-45s and A330NEO at the same time would be to have two separate production lines. Airbus would likely be loathe to do that. If Airbus had won the KC-45 contract, they would have been forced to create a separate production line for the A330NEO. Maybe losing the KC-45 contract was in Airbus' best long term business interests.