Well I would have thought BA wants the money. Franchises have traditionaly been on marginal routes which mainline wouldnt serve. I suspect these routes will be anything but marginal.
I think the problems of a JFK base are understated. Either they need a US AOC to fly N reg a/c which means max 25% UK owned. Or they need to base crews flying EU reg aircraft which would require green cards all round or US pilots with EU licences. Either way its a tough call to sort that out for may.