I stand somewhat corrected, yeah I know what you mean about CPH, they do offer a lot of connections, especially if you intend to go to Scandinavia/Northern Europe, but for Asia or America or even Europe, due to the necessary night stop (I don't actually know what time CPH's long haul departures leave) and higher cost, they aren't a big player. I'd say confidently that 90-95% of passengers on NCL-CPH are O&D. If the flight continued getting stronger and they throw a morning CRJ our way a couple of days a week, opening up connections then I can see success. Although I'd hope for an OSL service before a 2nd CPH service. Given their history though, I'd say that both are equally unlikely, I'd rather hold on to the service we have at the minute.
I had never quite realised Brussels Airlines' network was so vast! In that case, if all of those destinations are available as connections from NCL, I've underestimated BRU as well! and with 3 daily flights there must be connection opportunities...
I disagree with IST being at the bottom of the list but a FRA hub route (i.e LH) and MUC/MXP p2p (i.e EZY) are definitely above it in my opinion.