IP
Efficiently sending TV over the Internet is no technical challenge as existing regional distribution boxes could have proxy or multicast hardware put in them. The challenge, especially in the US, is all the greedy fingers that want a cut of the money. Toll trolls can't do anything about over-the-air TV because it's direct and uninterruptible. Cable TV suffers channel outages as the media company owning the wires battles the media company owning the programs for more money. Now imagine every ISP, from mega media corp to mom'n'pop, installing a hierarchy of simple TV proxy boxes. Toll trolls would have a feeding frenzy. You'd end up with such a ludicrous mess of DRM, activation dongles, usage tracking, ad injection, and fees that it would never work.