Any expansion they propose would be incredibly expensive, even for Dickie Scruggs. Their SEZ and east side are both permanently done. Their west side is done unless they're willing to tear down that explosion of suck known as their press box and luxury suites. They already seat a good deal in the metal bleachers in the NEZ. Any expansion there would delete those seats from the total capacity before adding back an expansion. And on top of it they'd have to contend with the field house that sits very close under those bleachers.
In short... I think they're 17'ed on any expansion plans for the foreseeable future.