Last time, I was talking about how an example Amtrak long-distance route, the Southwest Chief, could be segmented into day trains to serve intermediate points. I'd gotten as far east as Las Vegas, NM, and the next segment would probably be from there to somewhere in Kansas, but not as far as Kansas City. That's because this has historically been the slowest part of the route. It could be faster, but we'll talk about higher-speed routing some other time.
Some of a train route centered on Kansas City could overlap the Las Vegas to ? Kansas route, but the one centered on KC is going to serve a higher density of towns with more population as we get closer to the Mississippi. A KC to St. Louis train - rather than a KC to somewhere small near the Mississippi - makes sense, as does a KC to Chicago segment.
All this would take more locomotives and passenger cars than the once-a-day-each-way, current long-distance Chief, but it's something that would accomplish Amtrak's primary mission of serving underserved city/town pairs.
There will always be someone who wants to travel from Albuquerque to KC, and I don't think that establishing a train with those endpoints is out of the question, once the plan is proven and tweaked. It's not impossible to establish schedules where the segments make good connections, either, if the attention and cooperation of the freight railroads can be purchased.
So, if this were to work, we would have most possible city pairs along the route served.
The other mission of a national passenger network is to run trains between large city-center endpoints on a regular basis. I'll talk about that next time.