I'm going to take exception to this statement. It's probably true that the worldwide penetration rate of 1080p TVs is very little when you consider all of the TVs in the world, including 3rd world nations, etc. However, Apple isn't trying to sell to those people. They are trying to sell to people with HDTVs (or EDTVs). That drops the number of potential customers by a lot.
Then you have to figure that many newer HDTVs are going 1080p. You can debate whether 1080p is any better than 720p, but it's a losing arguement. In 2 years, the only non-1080p TVs you will be able to buy would be the low end, small TVs. More and more TVs are going 1080p. It's the new buzz word and it's what today's customers want.
By then, I would expect the aTV to be able to output 1080p and be able to run 1080p material. It's going to happen, whether we like it or not.
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The problem with 1080p isn't the unit or Apple it is the internet provider's bandwidth, infrastructure and your internet connection.
1080p won't be a viable option for the
tv for a looong time unfortunately.