12" Screen (same resolution as iPad Air 2)
A 12" screen at a density independent resolution of 1024 x 768 doesn't make sense IMO. The screen is considerably larger than a ~10" iPad.
Given the larger screen size in general, it is very possible that the iPad "Pro" would take on an aspect ratio that is closer to the MacBooks, i.e. a 16:10 ratio. Larger Android tablets take 1280 x 800 as their base density independent resolution (see Nexus 10), and I believe Apple will do the same.
Given the shift to @3x assets by Apple (iPhone 6+), I would think that a resolution of
3840 x 2400 is more likely, and would enable native playback of 4k (3840 x 2160) resolution videos. This yields a PPI of roughly 377, which is decent, and matches a 43% increase in density of the current retina "non-HD" iPad, closely matching the 50% increase from 2x -> 3x, and leaving the "touch" UI areas roughly the same.
This is what the screens will look like in terms of size comparisons -
http://www.displaywars.com/9,7-inch-4x3-vs-12-inch-16x10