Netflix’s purchase this week of North American distribution rights for the TV series ”House of Cards” is the clearest evidence yet of the transformation of the television business from one of programmed networks to one of unbundled programs. The event accelerates everything about this revolution, and those unprepared are likely to be caught up in the black hole that’s left behind. Make no mistake. This is the beginning of the end of linear television. So potentially complete is this transformation that it will impact everything from spectrum decisions in Washington to how things are bought and sold in the culture.