I think you pretty well answered your own question. There's already The Bear/Fox for rock currents and recurrents, and The Doc serving the classic rock audience. A pure Alternative, or classic alternative as it would most likely have to be, would further fragment an already small listener base in Centex.
Be content with what you've got. Several markets comparable in size to Waco, like Lufkin-Nacogdoches, Bryan-College Station, and here in Tyler-Longview are left with merely one outlet for rock music. In each case, it's a classic rock station, that just recently adjusted their own playlists to include the likes of Pearl Jam, Green Day and Nirvana, but don't hold your breath waiting for Tool, Corrosion of Conformity, or Korn.
My God, our own 96.1 was still playing Simon & Garfunkel and Steppenwolf up until last year. Y'all in Waco have it pretty good by comparison.