As you said, it's really difficult to project this, given how turbulent the media and conference landscape will be in the foreseeable future.
I do suspect the B12 will be earning more than the ACC relatively soon. There just aren't a lot of premium rights available in the next few years, and there is a serious demand on the part of both the traditional media companies and the streamers.
The B12 doesn't have the brands that the ACC does, but it generates more viewing. There is a lot of value there for both subscribers and ad sales.
And oddly enough, it's their lack of premium brands that makes them less likely to be raided by the SEC and B1G. Plus their leadership totally gets the new media landscape.