LOL NO, the tunnel in your graph shown is not open yet, it will be hopefully this year. Next thing you mention is Detroit which has a great train in the terminal, and so will SLC in another decade ( from what I read). I worked in Atlanta ( and about 25 other airports) and yes you can walk the gates and skip the train, which I did when I wanted a long walk, from check in to the F terminal is two miles in Atlanta. However my personal SLC experience pretty much sucks from the B gates. Last week it took over an hour to get my bags, that was after the walk to baggage, when they showed up they were all wet, I want to say an hour and 1/2 from when I left the gate, I guess it was break time, and trust me I have seen that one in action before.
On the plus side the rental area is great, check in is easy, and so is security. In the long run it will be a great airport. However for older people and people with little kids, I think it is a challenge from the B gates for now. My home airport is BNA these days, traffic can be horrific, and my neighbor is an airport consultant who designed the traffic flow, I need to ask him if the firm he works for designed SLC. That would explain a few things.