The plan is to build a three-story terminal building and two two-story concourses connected to the main terminal building via passenger walkways over the airport access road.The terminal will be built on and in front of the site of the current terminal, with the present building being demolished in stages.
The new terminal will have 41 gates, 13 more than the current building, and will encompass more than three times the floor space. Parking will be doubled, and retail space/concessions will increase threefold.
Here's the official Midway site with artist's renderings of the new terminal:
Also, here's a map of the development phasing:
The terminal will open in 2001, and the entire project will be completed by 2004.