VOD from the major networks will probably have a slower adoption rate. Their biz model is busted, but they have a lot of inertia. It takes them a long time to move, but when they do it changes the industry. See TV sets of DVDs. Before there was no way you'd see any sort of compilation before a show was sold into syndication (that's where the real dollars are), but the networks and the studios realized that releasing the DVD sets could capture even more fans and therefore drive higher ratings in subsequent seasons. As a result of the higher ratings, they can sell the shows into syndication for more money. It's a very nice circle.
It'll come. Just not as soon as you'd like. (Isn't that true about everything though?)
How do I know this? It's part of my job.