The cash incentive for ad revenue share on the TV will make it happen if it's ever going to happen. If it turns out people are willing to use the TV for internet searching the cable service providers will include a browser in their DVRs and start supplying a cheap bluetooth keyboard with the DVR as standard gear, just like the remote control. If they find out they can earn substantial revenue they'll give you limited free internet access via the DVR so some people that don't have much use for the web won't even bother paying for it if they can get it via the DVR. More importantly, some that don't use the cable broadband or use some other service will then give the cable operators a shot at a revenue source they didn't previously have.
If I were the cable company, the TV guide would be a web site, instant access, not downloaded slowly over time, it's a joke the way it currently works and I wish I worked there as I'd fix it but I digress...
FWIW, anyone with a game machine attached to their TV, like a Wii or a PS3 can already do it but the Opera browser stinks, doesn't support more than the basic stuff so reading PDFs and such doesn't work, most video doesn't play, and without a bluetooth keyboard it's kind of useless and most people aren't aware they can even use a blutetooth keyboard.
I also think high speed broadband everyone is clamoring for at the desktop is about to shift to 4G hotspots from cell phones and many will just dump their cable broadband altogether leaving the cable companies trying to recover that massive investment while the wireless guys are smiling all the way to the bank.
While it would seem we're drifting OT these changes, just like the smartphone, will also impact MS's bottom line unless they manage to become the DVR perhaps as part of an XBOX. They had some pretty good media software in Win Vista/7 then dumped it while Apple and Google are both making a strong play to get into the TV as my TV.
What that means is less MS desktop, less MSIE browser share, less Bing.
Wake up Redmond, the desk is being stacked against you.