That's a really good point that is often ignored:
As neat-o-keen as they are, no one actually wants to buy an ultra-portable.
Agreed, it is often an overlooked point. Still one has to consider...
I wouldn't have bought an MP3 player before the iPod, I was never moved to buy a game console before the Wii, and I never lusted after a PDA/smart phone before the iPhone. Sometimes a market direction has to be established or reestablished before a successful market exists.
I think Apple *could* do this with a tablet (especially now with a killer touch interface) but I am skeptical about an ultra-portable laptop. Seems a little too clunky for Apple to take part in.
-Clive