I read an interesting article conjecturing that MS's real goal in creating the Surface Pro was to drive their Hardware Partners to put out better devices to compete. Hmmmm, interesting and probably too clever by half, but it is a thought.
I personally hope they stick with the 10.6" and even go smaller, using an 11.6" tablet is uncomfortable, I did it for 2 years with the Samsung Series 7. The Surface is a Tablet First and laptop replacement second, the rigid keyboard dock Hybrids work much better in the 11.6" space as they are Laptops First and Tablets Second. Also the growth market is in the mini-tablet space. My dream for the Surface RT 2 is 8.1" with and Active Digitizer.