There are two expansions planned. The first one is already in process, at the western end of the terminal. I think this expansion is designed to allow for an A380 and perhaps also add a gate or two - I'm not certain. This expansion should be completed in the next year or so. You can see the steel girders being erected as we speak.
There is a second, much larger expansion also planned for Terminal E. This expansion will extend the terminal much farther to the west, all the way to the Delta hangar. This expansion will add multiple gates, expand the customs/immigration area, add an international lounge or two, etc., etc. I think this expansion is targeted for completion around 2020. Until then, we are unfortunately stuck with the congestion we've got.