Topend3,
Couldn't the argument be made that the AN A320s 'supplemented' the 737s?
As for the A330s 'replacing' the 762s... well, they're bigger than the 763s they're 'supplementing'!!
Can't see how it's such a different situation to AN. If QF had wanted to replace the old 762s, they could have got new 762s, more 763s or even 739s - meaning sod-all new crew & engo training. Instead, they've gone for an entirely new airframe/engine combo. In fact a strategy around 738, 763 and 777 would have had commonality benefits.
So... whilst not privy to the analysis, it would seem on the face that someone was possibly pretty keen to get a deal done and maybe offered to absorb some costs/give some guarantees.
Sounds a bit like a more recent deal... ???