The only reason to want Boeing to build it is to force some price competition on Airbus. Not to actually buy it.
I don't get this fascination with absolute maximum range. The vast majority of 757s, to take an example, were bought for notably shorter runs. BA were first in the queue for them, the majority of such flights being little more than an hour. Aircraft that are optimised for seven hour flights are typically giving away efficiency as a result on trunk short hauls, which is notably where the bulk of the market is. Even though 737s and A320s seem to have taken over US transcons (just about, in winter winds), the bulk of their flights there are for trips way shorter than this.