I think history is the biggest teller as to why airlines haven't jumped on the bandwagon. The only domestic routes that will probably make money in the UK flying jets the size of the A220/320 are your core trunk routes, Scotland - London, Ireland - London, Bristol - Scotland. I've heard figures being banded from senior management that these routes have to run at 85% load factor just to break even so that doesn't really beg the question why airlines aren't flying SOU - NCL etc on A319s etc, the answer is right there, just look at history, it doesn't work, the routes are too thin, it's the same as why airlines aren't operating out of Bournemouth in abundance; why not? It simply doesn't work, if it did you'd see them in there competing. If the A220 order books are full and they are difficult to come by this could drive up leasing costs, I can't see brand new aircraft having competitive lease costs flying thin, domestic routes around the UK. I wouldn't be so shocked to see it happen but I'd be more shocked if it was profitable. It is my opinion that even the A220 is still way off the mark economically to make such a pipe dream a profitable reality. Time will tell.