ESPN is making tons of money. Disney is simply demanding more. Losing those particular talking heads means that ESPN dumps their fat salary without affecting ad revenue or viewership. Will anyone stop watching MNF becauase Tirico has gone? Will viewers switch from a game on ESPN to NBC just to see Tirico's on-air performance?
That's different from passing on the B1G media rights, which in fact, most definitely will affect ad revenue and viewership. It's not apples to apples.
AS for the ACCN, a measure of reality is in order. You say it will make as much money as the SECN. How do you know that? If you're going to cite the ACC footprint, that's not news and it guarantees nothing. ESPN will have to go to the mat with cable carriers to get carriage. That can take time; just ask the PAC12. I can never get past the question, "If the ACCN is a slam dunk money maker, why doesn't it already exist?" Is ESPN just too lazy to go get the money? Now they are facing the prospect of paying the additional $45 mil in lieu of an ACCN. I think they will launch the ACCN only if the conference agrees to to a substantial extension of the rights contract. They risk (small risk, but real) of losing ACC schools to realignment. They want to extend the ACC media rights deal for as long as possible.
Suppose the ACCN appears this year. How does the conference get paid? ESPN owns the FB and MBB rights. They don't have to pay for that, and they won't have to pay the extra $45 mil. The conference can offer the non-rev sports. They won't get much for that.
If ESPN doesn't get a contract extension (which may be the only way the conference gets a raise) then ESPN will continue to starve the ACC until the expiry date is near. Then they will dangle the ACCN bait again, but for more attractive money.