It looks like Microsoft wants to cast NVIDIA and Intel out of its second generation Surface plans, in a likely effort to cut cost of hardware (on its end anyway). On the receiving end of things at their expense are AMD and Qualcomm. Redmond also plans 14.6-inch Surface Book. Turning the rumor mill is a leak from @MS_nerd, a fairly reliable source of leaks from Redmond.
The second generation Surface line of products, slated for next year, will see a Qualcomm-made chipset (probably just Snapdragon quad-core), replace NVIDIA Tegra 3 in the Surface RT; and AMD's "Temash" line of low-power quad-core APUs replace Intel Core i5 ULV dual-core in Surface Pro.
The Surface RT 2.0 will be built into the 8.9-inch form-factor, breaking away from the current 10.6-inch common physical size between the Surface RT and Pro. The 8.9-inch display could end up with higher pixel density, if it retains its current 1366 x 768 pixels resolution. The Surface Pro, on the other hand, could feature a larger 11.6-inch display. Since it's already beaming out 1920 x 1080 pixels, we don't expect the resolution to go up. If anything, the move toward a larger display is to spice up its desktop/laptop credentials.
The last sack of flour from the rumor mill reads that Microsoft is working on an even larger 14.6-inch device called Surface Book. In all likelihood, this could be a hybrid-Ultrabook with a solid keyboard/trackpad. Fortunately for Intel, it retains the powerful Core i5 "Haswell" processor.