Eye-tracking Kindle, Circa 2025.
It watches your eye movements as you read and pages when you reach the page turn icon at the bottom of the page.
(This is doable today but it'll take a while before they can get the processing power and algorithms out of the PC and into smartphones and readers.)
http://en.wikipedia.org/wiki/Eye_tracking
I'd still prefer the paging buttons on the basic Kindle, though.