Its interesting to read some peoples ideas(dreams) for NCL routes. I'm sure that there is a group of people expecting a new long haul announcement every week!
For a route to start, there HAS to be demand, not just a little demand that will fill the odd flight, the demand has to be more than viable. Then there is the start up costs, then the operating costs etc. If the route isn't profitable, it doesnt start. So don't be expecting 2 or 3 airlines fight to fly to NCL from the states, or other long haulers like canada etc crop up.
There is still a load of european destinations that NCL doesnt serve. Whether this is down to the lack of demand, or lack of bothering from management, i do not know.
If any of the likes of FRA etc happen, it wont be a 4x daily LH A320 or whatever, it will start of small and progressively improve. We wont be seeing the likes of Vueling take over from RYR, we wont be seeing Jet2 announce a host of long haul destinations from NCL to the likes of Canada.
If its purely down to spotters wanting to see long haul airliners, take a trip to one of airport in the UK that see them daily.