We know UA is using three-class 767-300s and two-class 757-200s as suppliments to their 767-200 fleet. We also know that the 762 fleet is going away soon (they were all sold for $16 million to a charter operation).

We have heard rumors and speculation that some 757-200s will either get upgraded First seating (probably the International First seat from the 767-300) or possibly even going to a true three-class configuration (again, with 767-300 International First and International Business seats). But all it is now is speculation. Internal UA sources either don't know for sure, or are sworn to secrecy.

My money is on CO and/or DL to be the first to place, with AA as an outside choice. Evidently CO flies 762s internationally (so sayeth www.seatguru.com), so that's a natural choice for a 7E7-8 or 7E7-9 in a two-class config (so you could get 250-300 people in it, probably). Same with replacing some 757-200s on the EWR-LGW route. Also, if CO or DL decides to stop being a 777 operator due to insufficient loads (I have no clue what loads are like, however), the 7E7 would be a great replacement for it and, in the case of DL, their MD-11s.

AA and UA could definitely use a 7E7-3 to replace their 762 fleet. UA doesn't have the money right now, and I am not sure AA does, either.

NW seems to have thrown their lot in with Airbus (A330s), so I don't see them as a 7E7 customer.