New York with United was an interesting experiment, a lot of flights went off with good pax numbers but with a 757, the cargo carrying capacity would have been minimal. Business Class seemed to have reasonable numbers (how many upgrades were involved, I don't know). Maybe with a different aircraft or even a different airline, things could have been different.
Will anyone else give it go? who knows?
Turkish Airlines to Istanbul would give a lot of interchange options and might not upset Emirates too much whereas Qatar??????