i am that guy that would buy this
If it's a screen way beyond what you get on an iPod touch or a phone, and its in Yeh iPad form factor (i prefer it on a tablet), and isn't £400 for a WiFi only model, maybe say 250 for an entry model, then I'd he very interested.
I don't need a ten inch screen, but do want something bigger than a phone... A decent 8 hour battery life, front facing camera, and access to the app store would be spot on.
Carrying around a full size iPad, despite what people say, is a bit of a hassle, so marginally smaller would be better.
A couple of feet from your face 7 or 8 inches is big enough. I wouldn't use it for typing at lengthy (no more than this post really) so wouldn't mind the smaller keyboard... And they could even split the qwert and yuiop onto separate sides of the screen in a smaller size for thumb friendly typing as I'm doing now on my phone. That'd be fine.
In short. Make it cost right, work like an iPad, look like an iPad, and not be excessively corner-cut-for-price and I'd get one. Maybe two, if the price was right. Couldn't blow a grand on one each for me out and about and at home, but 500 for two is much more like it.
Brings it into xmas present range for a lot more people too. They'd sell mountains I reckon. And still be able to shift loads of premium 10 inchers