Notre Dame isn't going to be able to preserve all of their rivalries no matter what. As conferences keep expanding and go to 9 conference games, some of them aren't going to want to blow 1 of their 3 out of conference games on the Domers every year. They've already stopped scheduling BC every year, for example. And because their rivals are all over the country, no matter what conference they pick they're going to lose a few.
Big Ten:
Michigan
Michigan State
Purdue
Big East:
Navy (in 2015)
PAC-12:
USC
ACC:
Boston College
Georgia Tech (to a far lesser degree than the others)
Miami
Pitt (in 2013)
Another way of looking at it is to break down the Irish's 2012 schedule:
ACC:
Miami
Pitt
BC
Wake Forest
Big East:
Navy
Big Ten:
Purdue
Michigan State
Michigan
Big XII:
Oklahoma
Independent:
BYU
PAC-12:
Stanford
USC
So 1/3 of ND's schedule is already ACC with 4 games. 1/4 is Big Ten, and the rest is scattered to the winds.
Of course, all of this ignores the biggest factor in Notre Dame's decision-making: $$$$$$$$$$$$$$$$$$$
Notre Dame to the ACC...