Your count for DL/NW is mistaken; you forgot the four daily frequencies NW flies to China from NRT that can be flown as nonstops from the USA mainland at NW's option. In addition, NW also controls some cargo-only frequencies, some of which may be convertible to passenger frequencies.

Given that CO/UA and DL/NW will control almost equal numbers of China flights, I don't see it as an impediment to approval.