If it's not Notre Dame, then I'm going to stick with my original guess from December: Nebraska. The school has never truly gotten along with the Texas contingent since the SWC-Big 8 merger and would stand to possibly double its annual TV revenue by joining the Big Ten.
Were the Big Ten to package the nationally revered Huskers with Missouri and one of the New York-area teams, it might as well start printing money. But that's just one man's guess -- the first of probably many to follow between now and July 1.