And if ND has so much Big 10 history, why haven't they joined yet? They are still likely to stay indy, but Big 10 doesn't seem likely.
LOL. I think you answered your question with the first statement following the question.
ND isn't in the Big Ten (or any conference) because they don't want to be in a conference. Period.
The only two scenarios where ND will join a conference are when either A.) Super conferences form and ND has to join a conference to compete for a BCS NC. or B.) The Big East falls apart and ND has no where to go for its non revenue sports.
If neither A.) or B.) happen, ND stays independent. Period. No amount of money will get them to join a conference. The Big Ten offered them nearly $10M more per year last year than their current TV deal was making them and they said no - they value their independence more than any amount of money that a conference could throw at them.