Re: 8-Inch Tablet the Ideal Size?
Keeping the 16:10 ratio intact, the Nexus 7 (which is presumably about 5.94"x3.71" would have to grow by 1.61" in length and 1.01" in width to gain an additional 1.9" diagonally (assuming the 8.9" rumor is correct). To keep the same pixel density it'd basically have to be at least 2442x1525 pixels, lending credibility to a QHD possibility, which would ultimately raise the pixel density to around 495 ppi.
Of course, the N8 could be 16:9, in which case these values change a bit.
On the subject of size, the Nexus 7 2013 is 7.87"x4.49" including bezels, etc (surface area = 35.34 square inches). The screen size of an 8.9" screen would be 7.76"x4.36" or 33.85 square inches. This would only leave .32" on the length and would leave us short about .23" on the width for bezels if we wanted to contain it in the body of a Nexus 7 (not sure why that's a goal), but essentially we're saying that the screen is going to be roughly 1/4 of an inch wider and and 1/3 of an inch shorter than your entire Nexus 7 (2013) tablet.
Obviously that's not what they're doing, but that could give us some perspective on how easy or difficult it would be to navigate it given the current familiarity of that device. The Nexus 7's bezels average out to about .53" on each side and .88" each on the top and bottom. They're a little huge, but if we took took those as a ballpark for guidance and normalized to assume we'll see about .25" to .75" average on all sides, we're looking at a device that's roughly the same form factor stretched out an inch or two on each axis.
It might be more accurate to think of it as something that's slightly taller than the height of the iPad Mini 2 and a little slimmer (due to different aspect ratio 16:10 vs 4:3). Having used an iPad Mini briefly, I liked my Nexus a lot better, but the bezel control on the iPad was much better and considering the two devices were almost identical in height, Apple crammed about 36% more screen area into a device that's the same height and where the N7 is using 62% of it's surface area as screen, the iPad Mini 2 uses about 72% of it's surface area as screen. Extrapolating the more generous of those two we could assume as total surface area of around 49.57 square inches, which in 16:10 proportions would (if 160x^2=49.57) indicate a device that is approximately 8.9" x 5.6" and if it's 16:9 then (if 144x^2=49.57) it'd be around 9.4" x 5.3". In either case, that's a little bigger than the LG G Pad 8.3 (obviously) and substantially smaller than the iPad and Nexus 10.