Google's obviously hellbent on taking over the living room, but a VAST majority of non-tech people I talk to are comfortable with their cable or satellite box, and are intimidated by "internet content"
My parents will set a DVR schedule to record a movie that's going to be on next week, when they could just watch it now on Netflix on their smart tv.
If cable and satellite providors, and hulu, and other outlets license current..let's call it "live" programming, then why can't Google create a "live" app, that's nothing more than a program guide, like we're all used to seeing on our set top boxes for years.. Users could scroll through the "channel guide" and the program would play, relative to the current time.. for instance, say Conan started at 9:00pm, it's 9:15. User could scroll down to TBS, select the program, and it would instantly start playing at 00:15:00 with a soft transparent popover asking the user if they'd like to start from the beginning, if not, popover fades, users watching the show.
While this seems like a ridiculous, counter intuitive way to stream video, it would be a simple, comforting interface that all tv viewers would understand, and could allow Google to break in to every living room in America.
Since programming is only available on a timed schedule, Google could even implement a "DVR" style interface that would allow users to "record" future events.. except instead of actually "recording" the program, it would simply wait until it's scheduled broadcast time, when it would just add the title to a "playlist" if you will... which would be similar to the current DVR recorded shows list. When the user picks a show, it starts to stream (since it's a historic show at that point).
Honestly, the only reason I haven't cut the cable yet is because while google play, netflix, hulu are all great things, I'd miss channel surfing, plus I enjoy local stations, and sporting events (mainly formula1 and other soccer games)
First local station/major network affiliates are easy: OTA antenna + DVR.
But the simple answer is money. A cable/satellite provider will pay a lot of money to have "exclusive rights" to network(s) content which then essentially requires anyone who wants to watch that content to subscribe to their service. ESPN/sports are a good example.
I don't doubt that many networks would love to sell their content via multiple outlets, but apparently the math says they would lose money from their bread and butter exclusive licensees because they would want to pay much less because they no longer have exclusive rights. There would have to be some sort of tipping point (most likely from subscriber losses which result in tighter profit margins) where cable/satellite providers are only willing/able to pay the networks so much while at the same time networks then determine that is not enough for exclusive rights.
Obviously some networks have worked into their exclusive rights agreements that it only guarantees the licensee rights to the first/live broadcast and that is why some content is available after this broadcast.