I'm not sure that I would agree with that statement.
The ACC has renegotiated and extended its ESPN contract several times already with the addition of new programs...
In July 2010, the ACC signed a 12 year contract with ESPN through 2022...in 2012, that contract was renegotiaited and extend to 2026 with the addition of Syracuse and Pitt....and again, later, the contract renegotiated and was extended with the partial addition of Notre Dame.
There is a clause in place that allows for the opening and renegotiation of the contract for any program addition.
I do suspect, that now, like the B1G and Big 12, the ACC might pay a partial distribution to a new member for a period.