Texas State and UTSA were added by the WAC, so even if C-USA took Louisiana, Arkansas State, and WKU a year sooner instead of Old Dominion, Charlotte, and UTSA - and Troy instead of Louisiana Tech - then the Sun Belt would have basically been left with ULM and South Alabama (who immediately filed to move to FBS upon expiration of the moratorium).

If the WAC were left with all three of UTSA, Texas State, and Lousiana Tech, then it probably would recast itself as a southeastern conference by taking in ULM and South Alabama. New Mexico State would be a full member, Idaho perhaps tolerates the setup instead of moving to the Big Sky, and then the invites for Georgia State (2013), Georgia Southern (2014) and Appalachian State (2014) are for the WAC, not the Sun Belt. Denver and UT-Arlington likely stay as well, and the WAC probably picks up UALR just to close down the Sun Belt:

Idaho
New Mexico State
Denver*
Seattle*
Texas State
UTSA
Texas Arlington*
South Alabama
Lousiana Tech
Louisiana Monroe
Little Rock*
Georgia State
Georgia Southern
Appalachian State (or Charlotte)

If Idaho still bows out, then likely the other of Appalachian State/Charlotte is next in line. If Seattle follows them out the door, then that opens up the spot for Old Dominion or Coastal Carolina.

All of the Great West schools would still be homeless, and Grand Canyon and Cal Baptist would be stuck in Division II. Even NJIT might be left in the Great West if the CAA and/or Big South had one fewer school to replace.