Have you tried Tivo? Thinking about this it appears that you can only get access to whatever catalog of media is available from the source(s) you are connected with. This could be via your cable, ISP, or internet and even OTA (over the air) methods.
Now imagine a box whereby you have several pipes coming into it. Verizon FIOS, Brighthouse, Comcast, etc., and someone on Kickstarter of in Silicon Valley programs code into this box whereby anything you search for is searched on all the different pipes or connections. Then by pressing a button the remote or clicking a link on the tablet, you get access. Yes, it wouldn't be affordable to some people but if it caught on, who knows. I could see the cable companies working together to provide this capability and offer the box as well. Some lucky developer could stand to make a huge sum of money on this idea. Who wants to start? ;)