And are all these new TVs fully inter-compatible with each other?
Why do TVs have to be 'fully inter-compatiable' w/each other? The TV has apps for Netflix, Hulu, Vudu, ESPN, YouTube, Amazon streaming, Pandora, NHL GameCenter, etc., and you just launch the app of the content you want to watch. A Samsung TV doesn't have to be able to talk w/a Westinghouse TV, they just both need to be able to talk to the app's servers.
W/that being said there is a group called DLNA which is trying to get all manufactures to adopt an open standard so that all these 'smart' entertainment devices can easily stream content/pass files between each other. If you have two DLNA certified devices they should seamlessly be able to talk to each other over the same WiFi network.
I know Netflix support is common, but secure content distribution among networks? Does Hulu play nice with non-supported networks? I doubt it.
I don't follow what you are asking. Are you referring to data networks, cable networks...?
And what about all the people that don't have newer TVs?
See my previous post. There are dozens of devices that let easily and simply let people stream IP-based content to their TVs (including sub-$100 Blu-ray players).
Do the newer cable boxes support internet content?
No idea, but cable providers Xfinity and Verizon allow their subscribers limited streaming of their content via an Xbox360 and AT&T & Microsoft had a deal going where instead of a 'cable box' from AT&T for its U-verse service you could use an Xbox360 (according to AT&T this program has been temporarily suspended pending upgrades).
A cable company needs to be concerned about their content delivery, not 3rd party equipment.
Content that used to be exclusively in the realm of cable TV is now available (legally) via other means and that trend is only going to grow. 5-10yrs from now the content delivery business is going to look much different, and much broader, than it is right now. So, is TW Cable in the cable TV business (which is a business that's headed for contraction, not growth) or are they in the content delivery business (which is expanding and involves devices that easily allow Internet-based content to get streamed to a TV)?
It's like the old adage about all the railroad owners that went under because they considered themselves to be in the railroad businesses and not in the transportation business.
Lethal