The idea, presumably, is that there will come a day when more P-8s can be acquired. However... the whole idea seems to be based on (1) minimizing upfront cash,
the LCC and (2) a perhaps well-founded fear that if we try something new it will turn into a gigantic cockup. Sad, in a way, because there is likely to be a nice little global market for MPA/ASW and not everyone will want to spring for the P-8A and its US-priced upgrade packages.