If, as some state, the Big Ten could go beyond 12 teams and expand to 14, I could see the ACC doing likewise.
Picture these changes:
Big Ten adds Maryland (from ACC) and Rutgers and Syracuse (from Big East). Maryland might be a darkhorse, but it could use the boost from Big Ten football, and with those three schools, the Big Ten would be set from New York to Washington, the prime eastern seaboard.
ACC then adds Connecticut, Pittsburgh and West Virginia from Big East. UConn complements Boston College, while Pitt and WVU complement each other.
The odd folks out in this would be Cincinnati, Louisville and South Florida, the three remaining Big East football members. Where would they go? I could envision Cinci and L'ville being picked up by the Big 12 -- Kentucky borders Missouri, and both schools have history with Great Plains competition from their years in the Missouri Valley Conference. USF is odd man out; I don't see the SEC taking it in. It might have to go to a non-BCS conference.
And the Big East could go back to its non-football origins.
If pretty sure though that if the Big Ten were speaking with Maryland at some point in this scenario, that Maryland would also report back to the ACC. It's all part of negotiations. So put aside how much of an extreme longshot Maryland leaving would ever be. Instead, look at it as business negotiations: Maryland tells the ACC that the Big Ten might officially invite them and the average yearly revenue will be X dollars. The ACC then considers it's options: let them go and replace them, or follow suit and expand to 14. The ACC would then look to work with Maryland to find suitable members. So perhaps it's as simple as an ACC North division being created by inviting Syracuse and Rutgers (BC, Syracuse, Rutgers, Maryland, Virginia Tech, Virginia).
Who knows but I feel dirty anytime I try to make a rationale point and it includes a 14 team BCS conference.