I absolutely love the new SLC and the Delta Sky Club is spectacular. It looks like they're making great progress on the new tunnel and the east side of Concourse A.
If my French Bulldog can make it from the B gates to National Car Rental reasonably, then I think most passengers should be able to without dramatic complaint.
I do wonder if they'll put in a train before Concourse C becomes a reality... But I don't think it's necessary when you see DTW and ORD not using a train for the parallel concourses.