If the good people of NI want a US link, then right now Norwegian offers their best shot, they are the launch customer for Europe for the 738MAX with the first aircraft arriving in 3 months and will have 6 by the end of June. These are ETOPS spec aircraft, nothing else comes close in min fuel burn terms for 'thin' routes.
EDI is being set up as a narrow body long haul base and whilst the routes have yet to be formally announced its no secret that they are look at BOS/JFK bay area, but not necessarily JFK OR BOS.
I would expect a slow ramp up with aircraft routing through EDI/BFS/MAN/ORK/BHX & maybe STN
Who else could do it?, not Jet2 with the 757 and they are unknown in the states, a legacy may jump in as a spoiler, but thats unlikely.
Norwegian have huge brand awareness at both JFK and BOS, getting the cost down will be key, so secondary airports no APD and so on..
Norwegian maybe waiting to see what the Donald does about their approval before launching the route, but his in tray is getting fuller by the day.