With news that the Big East could be losing its basketball members (not to mention the speculation of Boise State and others not sticking around to play even a single game in the conference), there's now something else to consider -
The speculation's out there, though not much is known just yet. But if the Big East disbands, that would obviously free up both schools to join early. The ACC would need to do some scrambling as officials may not have been expecting both to be available this soon. But if things progress quickly, they should be able to figure out the scheduling without too much trouble.
The Big East situation really needs to be resolved soon. If the league doesn't get dissolved right away, but does fall apart before next season, I'm not sure what Louisville and Notre Dame would do if the schedules are already set. But with an early exit looking like a possibility, you can bet that the ACC is likely going to wait as long as they can before finalizing a schedule.