Here's what I know about the "Airport Expansion"
Here is a outline of what I think the new airport with the layout over the old could look like. Since I work at the airport I do hear alot of rumors of the Expansion. So here is a layout of what I know and what some of these rumors are.

Photo from Skyguy414
Red: Shows where the new concourse/gates could go. My understanding is there could be two or three concourse with a underground subway to connect them all. Notice on the far left side where the dirt is. Looks like crews have already cleared out that area.
Blue: Blue shows where the Rent-a-cars lots are right now. Alamo, Dollar, Hurtz, ect. These lots will be clear out to make way for the new airport. The new rent-a-car lots will go in the big field right at the entice of the airport. ( Not show in Pic )
Green: Shows were the 4 level parking garage is now. That will also come down to make way for the new airport.
Light Blue: Shows where the new terminals will be. My understanding is there will be three terminals just like what we have now.
Black: Shows where the new road to the entice of the terminals will be. Pick-ups/Drop-offs.
Yellow: Show where the Trax line could go. I know there will be a Trax line and stop somewhere in that area.
Purple: Shows where the new parking garage will go. It will be bigger then the one we have now. Not sure how tall.
So that is what I know. Not sure when all of this is going to start. If anyone knows more feel free to add to this.