One thing to keep in mind with the B10 expansion is the Big Ten Network's deal with Comcast. Their contract says that Comcast will put BTN in their basic cable package for every subscriber located in a state with a B10 school. That means that if the B10 adds a school from a "new" state, Big Ten Network gets subscription money every month for every Comcast subscriber in that state.
(I've heard it's $1.10 per month, per subscriber).
That's why I don't see Iowa State, Pitt or Cinci as real possibilities - because there is more money to be made by adding a school outside of the existing Big Ten footprint, like Texas, Missouri, Syracuse, Rutgers or Maryland. (I purposefully excluded Nebraska because they don't bring any big TV markets with them).