The 93.1 frequency would go back into the general allotment pool, perhaps auctioned off in the next two-three years and then it would reappear on the dial in the next four-five. In the near term, however, the FCC would actually completely remove the channel from the engineering database. Someone would have to specifically petition the FCC to put it back into the FM Table of Allotments.
If I had to predict what would happen - SSR Communications, Inc., Licensee of WYAB, will likely petition the FCC to add 93.1 back into the Table of Allotments to some deserving community of license - possibly Yazoo City, Benton, or some other community. The FCC would eventually take SSR's application, along with those of other interested parties, into an auction setting to send off to the highest bidder.
The "new 93.1" may then appear sometime in 2012/2013, depending on who actually wins the license at auction.
--- Casual Observer