A numbers game
All phones and (t|ph)ablets are basically the same. They perform the same functions: primarily running apps, occasionally taking photos and rarely making calls.
As such, to the man in the street, their only distinguishing features are brand recognition and the numbers touted in their specifications.
It seems that there are only two numbers that people either understand or care about. One is the number of megapixels the camera claims and the other is the size of the screen. MegaPix seems to be a busted flush, since the numbers are getting so large - yet the picture quality of a 20 MPix "phone" is no better than a 4 MPix phone's. And when you view them on the screen they are the same.
So stop pushing camera specs and focus on the other number. However, buyers will soon tire of over-large phones. Whether due to their unwieldy nature or their excessive weight. I can't see many people wanting to lug an 8-inch screen around - we had that with laptops.
Personally, I'd settle for any size screen. Just so long as you could see what was on it in daylight.