I don't think the online advertising model is a failure - I just think there is a lot more room for increased ad volume with it. As traditional media outlets decline, we are going to see more and more of that room exploited on our screens.
As far as AdBlock, no company wants to pay for eyes that they are never going to get on their ads. There was (and is) plenty of resistance to TiVo from the networks because they know that companies do not want to pay for commercials that consumers using TiVo can and will skip.