It seems like the chances of UA expanding operations in MEM are pretty small, but if they did there's room for a polaris club between A and B.
I agree with you. It seems that people think that the big 3 should be able to have a large presence everywhere in the country. But to defend everything is to defend nothing.
DL is bad in TX
AA is bad in the Pacific Northwest
UA is bad in the SE.
WN is the best at covering the lower 48, but their horrible if you need to go to most second, and nearly all third tier cities or TPAC, TATL, or S. America or Canada or a non beach MX destination. And they can't get you to AK or HI.
No one carrier can have it all. IF they could, someone would have tried it by now!