It would probably be the best move to keep the B12 from falling apart. It would make the most sense for the Big-XII to add 2-3 teams out west in BYU, Colorado St., and Boise St.- CSU and BYU both add good TV markets, CSU could easily overtake Colorado as "The School" in Colorado if they had P5 inclusion. Boise St. football also has a good reputation and interest nationally but has a lot of room for improvement.
Back east, UCF is really the only move that makes sense IMO. Opens up the state of Florida, and adds a decent TV market. Cinci is solid, but is in a market dominated by Ohio State- With 4 or 5 other major players in neighboring states.