The current "expansion" is on the west side suites and press box. From what I understand, they are filling the gap between the decks and creating better suite views. The next expansion will start after Disch-Falk's expansion/renovation is complete. It will tear down the north endzone horseshoe and rebuild it closer to the field. I'm not sure if they will do the upper deck on that section at that time or if it will be a later addition. Those expansions will apparently send the stadium well over 90,000. The last stage will be the south endzone, which will supposedly happen within the decade. That all should total around 115,000.
Future at 114,000
From UT's masterplan document.