IMO the only school the Big 10 really wants is Notre Dame. It balances the conference and gives them yet another national collegiate marketing super power. If they get ND I believe they won't want anybody else. Every other possibility just waters it down, creates more scheduling and travel issues and brings relatively nothing to the table in comparison to what they'll have. Notre Dame along with Penn State locks down the NYC metro on Saturday Afternoons and evenings, they'll dominate every media market from Boston to the Twin Cities, and Illinois already gives them a huge chunk of St. Louis, and ND only adds to that. What do they need Moo for, what do they need Cornhole for . . . they don't.
So the key is ND, if the Big 10 gets them, that's it IMO.