A multi-touch screen that big would be pretty amazing. You can get a bunch of windows boxes with exactly that, but of course the software isn't there. What we need is iOS on a massive screen.
Problem is, something that big isn't going to be portable. You're not going to hold it in one hand and use it with the other. You'd want to use both hands on it anyway. So it's going to be desk based. But not like the iMac, that doesn't work - you can't use a touchscreen vertically, you'd get gorilla arms fast. It has to be nearly flat, like a keyboard. And with a touch OS you're not going to get a keyboard + mouse.
So what is it? It's just a big desk-based tablet running ios. Thing is, there's probably not much of a market for that.. yet. Give it a year or two and maybe we'll see it