Would a UA 757 staging through Ncl to maybe Frankfurt or Berlin work? Of course dropp
Simply put, NO!
Berlin and Frankfurt work well for STAR as direct connects. Why, in this day and age, would a passenger choose (say) FRA/NCL/EWR over FRA/EWR at the same cost - economically it would not be any better priced? Fact is, NCL has always been a thin route for UA, their local sales manager has already admitted so to the trade regarding revenue and load.