Right now, on the ground at MEX, there are two 321Ns one headed to Tijuana and the other to Mexicali.. Both are equivalent distance to LAX/ATL/SAN and they are somehow making NEOs work out of 7300' elevation.

Chicago and Bogota (high elevation both ends) on a 321N

AeroMexico is doing JFK-MEX on a 320Neo, but not sure if that's a 320 for performance or sizing to network. (as we are partners and have a daily 757-200 and occasionally a 763ER on the route)