I've got the answer - lay the iMac down, insert into a desk or coffee table so it is level, like a big iPad! With a touch screen it would be great for gaming - imagine PONG on a Retsina screen!
A bit like the Microsoft Surface.
I think the touch screen patent that Apple did last year looked pretty awesome.
Some are crazy; some arn't.
Trackpad as standard What sort of dreams are you having? - Why not a holographic trackpad projected on to your table?
3D viewing capabilities (although could be a messy complication for something which may not last) Without glasses would be cool, but expensive. With glasses would be cool, for the few 3D games and the few 3D blu r... I don't think Apple will do this; I think, by 2012 / 2013, when it is certain if 3D is going to catch on / be a flop, Apple may put a 3D-no-glasses display in their iPad, by iPad 5. The 3D would be very cool.
1080p input (as with my thread) HDMI? For your PS3, and your blu ray. Apple may do this (1 in about a thousand chance).
USB 3 That'll happen in 2012, when Intel adopts USB 3.0.
Slightly improved bass in speakers That is probably going to happen, they're always improving things like that.
Slightly lower price
Design to stay the same (its beautiful)
I'll add: Light Peak By 2012 max.