Many people want a-la-carte cable where they get to pick what they want - why not video services? Why not have it be so open that anyone can provide anything to anyone else, ala the more open app stores?
This is the route that most of the settop box vendors like Roku and Apple are going, and I tend to think it'll win in the end.
Aggregators like Netflix survive based on their marketing and negotiating strength, and economies of scale with servers and such. I tend to think that the latter will become less of an issue as technology progresses, and the former will be around as long as people are making media - this entire thing comes down to setting a price on specific content.