ND's performance in this year's CFP added five years to whatever the anticipated date of them needing to join a conference for all sports had been.
For the sake of discussion, if the ACC were to consider the K proposal, I don't see how they could all the entirety of the current BE. The 18 member (until they lose a couple) football conference may be workable, although far from Ideal, but a 29 member basketball conference would be absolutely ridiculous. Logically they would want to cap it at an even number, most likely 24, which would leave nearly half of the current BE out on the cold.
I think K is just trying to sound like he cares about a number of schools that his conference spent decades repeatedly trying to destroy.