A small change in screen size will not affect the usability of touch interface. The hell it won't. Right now the screen on an iPad is 5.86" by 7.79", for 9.75

A small change in screen size will not affect the usability of touch interface. The hell it won't. Right now the screen on an iPad is 5.86" by 7.79", for 9.75" diagonal. Multiply those dimensions by 90%, and you get a diagonal length of 8.78", an inch smaller. Except you've just cut the total area of 45.6 square inches down to 37, a difference of 19%. In other words, you've just reduced the area of every tap target by one-fifth. Put another way, you've created a fuzz factor of one-fifth in the size at which designers will have to expect their work to be rendered. It doesn't sound to me like an acceptable strategy from the Apple, Inc of this dimension. I'm not saying your conclusions are wrong — I think Apple's going to have a robust presence at the low end of the market. I just think they're going to get there by defining the low end as last year's iPad, not by kneecapping their own margins, or introducing compromised products.