This is many years premature. It may come to pass, but is nowhere near that now. TV is still by far the most common way of watching television shows (and watching television shows is still the most common way of wasting time) and overall viewership is increasing every year. This trend doesn't seem to be changing for a few reasons.

1) TV screens are much bigger and cheaper. They don't need the resolution a monitor does. Watching on a small screen is something you're happy to be able to do on a plane, but would never want to do on a day to day basis.

2) Bandwidth is still not there, especially for HDTV, and progress seems to be stalled. I still have pretty much the same connection for the same price that I did 5 years ago, and I'll likely still have it in 5 years from now. Mark Cuban talks about this a lot. Fiber to the premises may solve this one soon for some subset of the country, but by no means everyone.

3) Live television is nearly non-existent online. It can't handle it. The bandwidth to stream the Superbowl to everyone who wants it doesn't exist. Sports are a huge part of the TV viewing audience.

4) Many people like to watch shows as soon as they're released. The internet is terrible for this. I personally download mine, but I do so knowing that I'm always going to be watching the Daily Show from 2 days ago. If I were a TV addict (i.e. normal American) that would be unacceptable.

5) Content quality is better than ever. Single camera sitcoms, pay channel dramas, reality tv (if you're into that). Almost everyone agrees this is a golden era of television.

If you really think that more people are watching TV on a computer than on a good old-fashioned TV, you need to come down from your Silicon Valley mountain for a while.