UA Fares ex NCL
I think the views expressed re next summers UA fares are perhaps somewhat parochial in that you are simply considering one destination. The whole point of the UA flight is to offer service to NYC & BEYOND. It may be that the incremental cost of NCL to LAX,SFO, ORD or where ever come in pretty keen. Who knows & if all one is doing is to access comparative fares from one of the many internet based search engines then you may only be provided with part of the picture.
I personally find all this discussion on UA fares presumably in an attempt to judge demand / potential success futile. At the end of the day UA will work within market forces, & without an insight into their marketing strategy then current observations reveal nothing, and as already noted are actually negative.