It’s been a while since I flew through SLC, so when I flew through last week, I noticed right away that there were some extra concourses nearly on top of the existing terminals.
New Concourse A, as seen from existing Concourse E.
It turns out that SLC is building a pair of replacement concourses on the site of the existing concourses. It looks like their intent will be to move existing flights from the existing concourses C/D/E/F/G to the new concourses A and B, tear down C/D/E/F/G, and then possibly expand A and B to the east.
Older Versions
Paul Bogard created these terminal silhouette illustrations, and has made them available for use under a CC BY-SA 4.0 License.