I've been flying UA from DFW for almost 20 years. I just find the frequency shift interesting. They always had flights to all hubs during this time (pre and post CO), except when they finally dehubbed CLE.
SFO and IAD are the most interesting routes as UA has sometimes gone as low as 1x (with IAD, the 1x seemed to be timed with the European flight bank). SFO is now up to 4x with half mainline and half express, which is about as high as I have seen it over this time. True, DL and NK are not competing on that route, but I am surprised that LAX went away completely, especially with the international routes from there. I would have thought they would drop LAX down to 1x, like they have done with SFO and IAD in the past, not 0.