Kevin Gammill, the program manager for Microsoft's Xbox Platform Partner Group, said that the console would output at 1440p if a 1440p monitor was detected.
I understood what he meant. Rather than saying the resolution is sub 4k and therefore super sample at 1080p, on a 1440p monitor the X will super sample from 4k down to 1440p instead. Great news for those that game at 1440p.