My personal opinion is that I doubt NYC will ever be more than a couple of shopping weekend trips for the following reasons:
-United decided that it could make more money in LHR than it could from BRS with its vast catchment area and being in a very affluent area.
-NYC is reachable just up the road in EDI or a couple of hours away in MAN.
-As the US majors scale back their 757 operations, competition between destinations to be served by the 757 will be fierce.
-Once the 757 goes they are left with options - all of which are just too much jet.
-Lack of inbounds. This would be North Easterners going on their jollies and I can see very few inbound visitors from the US. The NE is not a tourist hotspot. Before anyone jumps in listing tourist attractions, I don't doubt there will be some visitors, just not enough to fill a 757 regularly.
-Regular and flexible options via AMS, LHR, DUB and CDG. Yes the flight would be direct but the business folk want choice.