Remember, the Big Ten is now a cable network, and ideally they want to be a national expanded basic cable network. Any expansion target must deliver TV sets by population of the home state. Whether the school actually has a following throughout its state is irrelevent (Syracuse). The payday from TV subscribers/per household more than offsets ad revenue (again, Syracuse, and Rutgers). OTA networks need viewers, cable networks only need subscribers. Big difference.
Jim Delany is a genius, and its not by accident that he's often mentioned as the most powerful man in college sports.
All that said, the Big Ten is not interested in annexing the 1500 TV sets with antennas in Oklahoma (or West Virginia or Nebraska), nor can Jim Delany honestly pitch any of these as viable candidates to the current Big Ten school presidents.
The options are, IMHO: Texas, Missouri, Syracuse, and Rutgers. That's it -- that's the whole list. The only way the Big Ten "settles" for a school already in a state currently occupied by another Big Ten school is if it's Notre Dame. Either go to 12 (Texas) or goto 14 (Texas, Missouri, and Syracuse). Don't jump to 16 (or more) yet. Make the move, see what the Pac 10 does (and what happens to the Big XII after it collapses), get to 14, then the Big Ten has 2 more slots left in the bag for future considerations if there is a shift to 4 16-team Super Conferences.