WW mentioned that EI might give up on 321s, Mark D. This was within the past few months - in fact, around the time the first of the new tranche of A320s was delivered.
With regard to Belfast having links to a number of UK airports, I really don't think that would hold water; the same thing was said about JER, when BA took our flights away. That's all well and good, but it's still a long, dull journey on the bus along the M25, which can often be a lengthy, delayed and tedious experience.
It's quite easily arguable that NI's economy could be badly hit by this. As I said, the political reaction to any proposal to cut routes would be pretty vocal.