As Chad Scott pointed out (HT EO) ESPN owes the ACC $45 million dollars this year if they do not launch the ACC Network by July 1, 2016. July is still far away, but I don't think the ACC and ESPN are going to rally and launch a network in three months. It looks like the ACC is going to get the money from the network without having an actual network.
The change in plans is very much due to the cord cutting phenomenon. And while the conference will lack the cache of having its own network, this is probably a better deal. In this set up, there is no financial downside. ESPN remains very much in bed with the ACC, plus this sort of deal incents ESPN to put ACC content on its own channels and in key slots. I've joked, but ESPN U will be the default ACC Network.
The extra money would move the ACC TV deal closer to the SEC's and the Big Ten's. Plus there is still a chance to have a true network in 2017 and beyond if the economics or marketplace change.