I would be curious how an ACC/Pac12 merger is even possible. For that to happen ESPN has to agree to add 10 Pac12 teams to its ACC deal. At $17M/school that would be around $175M. If the Big12 adds 4 corner schools that's around $80M incremental investment for ESPN ($31.7x60%x4).
If ESPN isn't willing to be an aggressive bidder in the ongoing Pac12 media rights negotiations, why would they want to invest hundreds of millions to add Pac12 schools to the ACC? And I believe the current ACC deal with ESPN is for less money than the Pac12 is hoping to get with their current negotiations.
Not sure where the recent interest in an ACC/Pac12 merger comes from. About a year ago the UNC AD Cunningham brought it up in an email, but that is old news. I feel like Cunningham was using the merger as a tool to cause ESPN to reopen its deal with the ACC. With the economy trending down & ESPN laying off people, it might not be a great time to push ESPN. They might just tell the ACC they can do so only by breaking their deal with ESPN.
With the Billions that ESPN is going to invest in the upcoming 12 team playoff, it might prefer not being saddled with the ACCN deal ($250M+ annually) through 2036. It's not like ESPN doesn't already have the inventory with their SEC & Big12 deals. If anything, it would seem to add value to the SEC/Big12 deals as more football and basketball games can be shown on ABC, ESPN or ESPN2 where advertising rates are higher than SECN or ESPN+.