I think jetblue would be wishful thinking, although they have reported a solid earnings increase of late. It doesn't even currently have a capable aircraft of making.
Jetblue makes a profit on doing what it does well, it won't rush to international expansion.
United Continental I don't see.
I think the current US market is too volatile for a risk, and Newcastle would be a risk. To an American exec the drive to Manchester or Edi or the transit to AMS or LHR is probably seen as not a big deal and a bit off putting