I'm still waiting for them to release some sort of touch/type cover that makes use of the power connectors found on the surface pro 1.
My prediction for the upcoming surface pro 2 is simply that it will have haswell, longer battery life, possibly thinner/lighter.
The Pro 1-2 compatible battery cover news was posted some days ago, and they're supposedly being released at the same time as Pro2. I highly doubt Pro 2 will differ much in weight/thickness, because if Haswell is purported to squeeze an additional 2 hours, the assumption is 2 hours based on existing battery capacity.
I can't imagine using MS Office documents on anything smaller than a 10" screen. Full mini-computing smaller than that reminds me of the OQO, and we all remember how well that did, right? You're not going to stuff much of a battery in a 7" chassis, either, unless it's ARM architecture again. (The OQO was an inch thick or something.) iPad Minis do well because they do so little, as a giant phone and smaller e-reader; what would a Surface do in comparison, when both Surfaces already did so much more than iPads? I don't think it's a good idea at this juncture because the physical properties really put a hard limit on functionality at a certain point. It'd probably end up being a pure e-reader consumption device as well, sort of a waste of development resources, IMO. Unless the functionality is greatly reduced, a full mini-computer in that form factor will probably die like the OQO--unless the OQO really was a decade ahead of its time and consumers are ready now. I don't believe they are, but MS may do the gamble anyway; I suppose they can afford losing that particular gamble, though.
I currently have an Acer W3 8.1" Windows tablet and would love if MS released one of Surface quality. If not MS, then a Nokia branded one. I can do without the desktop mode, I hardly go to desktop on my Acer, I mainly use it for the Modern UI, which is what I want out of a sub-10" Surface RT. I don't need full Windows on a sub-10" tablet, so I'd be happy with an RT version.
I do the same as what iPad Mini users do, media consumption and playing with the apps. Don't get me wrong, I enjoy my Surface Pro very much, but I don't need all that computing power ALL the time. Like with the Acer, I usually take that to work because it's much easier to carry or place in my bag. As for office, I sit in front of my PC all day at work, so any document work I need done, I have my work computer for that.
Pretty much I would use an 8" Surface RT for media and to app play with. Not much for work.