Pretty spot on. Couple thoughts:
The ACC's contract looked terrible at the time they signed it, but it is actually getting better. Just not better, fast enough, to match the SEC. This is because they gave away decades of not being able to go to market so that ESPN would give them the ACC network. It is just now starting to gain traction and their revenue is increasing because of it. Third tier rights are nice, but don't match T1 games in terms of revenue, and that's where the ACC won't catch the SEC for a long time, if ever.
The B12 never formed a network because their households weren't awesome and they never had enough inventory to fill one, its basically sold content to FS1 and ESPN+ and this didn't change with the move to 12. With the move to 14 and perhaps 16, including their households doubling from 10 to 13, they would have the extra inventory and markets where they could form one in the right conditions. With cable losing 36% of its homes over the past 5 years, would they want to?
The ACC and B12 are two different peas in the same pod, financially. The ACC has 2-3 major draws, 3-5 duds, and some solid middle. The B12 lacks both major draws and duds, so its just a solid middle. The ACCs highs are higher, but their lows are lower, evening out their network value. This could change if the B12 grows to 16 with even money plays. They'll end around 34-38% below the B1G's set ceiling, higher than the ACC, and with the ability to prove they deserve more money 5 years before the ACC can even go to market. This is likely the main reason FSU wants out of the deal it forced on the ACC. It expected to match the SEC with its own network, but that was never going to be the case.
The Pac had a great contract, best in the biz for a moment, but destroyed it. Seven channels was too many channels, too much expense, too little payoff and it was evident two years into the experiment. Now they're at the point that if Arizona leaves, I'm not sure how the Pac remains in the same conversation as the ACC/B12 as long as Oregon/Washington want a new home. They could add SDSU and SMU, but even if they're worth $200m a year, Oregon/Washington are 40-50% of that contract. If the B1G takes them or turns to them and says, "we will never, ever want your wagon wheel coffee table" and they join the B12, there is nothing left, due to geography. It is really a shocking case study on how 12 schools with the brightest minds and massive business schools ran their own operation into the ground.