Jenkins:
I don't know when Eastern's J41 leases expire but obviously their lease rentals are non-negotiable until then. Come lease renewal time, of course there's scope for change, but there's not exactly an excess of demand over supply for Jetstreams at the moment so I would have thought that flyBE (if indeed they are the beneficial owners of the aircraft) would just be happy to be getting some revenue stream rather than driving Eastern to take other J41s. So I wouldn't see that as a major threat to Eastern's cost base.
Incidentally, ACAS says that the J41s which Eastern operates but doesn't own are owned by a company called "Trident Aviation Leasing" in Jersey. Are you sure that the ultimate owner of those J41s is BACX/BA Connect (and hence perhaps now flyBE), or did big BA keep the ownership?
C.