I see your point, ornithopter but consider if 40 777 captains jumped ship at the same time, for example. The operation would come to pieces. In principle, this isn't as outlandish as it may seem as a few senior guys could jump early to protect whatever pension they currently have.
Practically though, it would require a lot of coincidences:
BA being prepared to risk everything to railroad pension changes on the pilots; Etihad/Emirates/whoever being in a position to open a London base at around the same time; slots becoming available at LHR/LGW for these companies to justify expansion.
Certainly the latter would only happen if BA was prepared to risk everything and their bluff was called, in which case there would be a lot more than 40 pilots from BA available.....
