If Notre Dame wanted Navy in a conference with Notre Dame, they could arrange that with the ACC by joining and requesting it. If you read any of the articles out of Notre Dame about their play in the ACC for things like Women's Soccer or Men's Soccer, they all start by calling the ACC the country's best soccer conference. I just see no signs whatsoever about Notre Dame being unhappy. I also don't know if Navy would be who Notre Dame would prefer as number 16 if they joined.
Most of what I'm reading about the Big Ten adding anyone else is that they don't want anyone else until at earliest 2017.