If the Pac-10 swiped six teams from the Big 12 and Missouri or Nebraska went to the Big Ten, the Big 12 would become defunct. Under N.C.A.A. guidelines, a conference needs at least six universities that have played together for five years. The Big 12 would lose its Bowl Championship Series bid and automatic bid to the N.C.A.A. basketball tournament. That could leave colleges like Kansas and Kansas State to be snapped up by the Big East, which could be its best bet to continue using the lure of a B.C.S. bid for football recruits.