here in the UK, I have NTL Cable TV installed. This comes with a service called 'on demand'; free and to-purchase programmes and films... kinda like iTunes store, but for the TV.
if Apple think about it... integration of this and similar services (sky+, skyHD etc) would please the current eyeTV users and push the TV on demand / online content even further.
Channel 4 (UK) currently do 4oD (4 on Demand) on the web. I don't work for them
This could then be streamed across your network and watched on any Mac, PC or other TV with iTV attached. There is one limitation straight away and that is only one device can control the non-web based content i.e if you receive cable and have only one cable box, you can only change the channel one on device - kinda like in the bar when they change the channel on the tv and all the tv's change.
iTV could also phase out the Airport Base station and Airtunes hardware.