I think that replacing Windows RT with full Windows on a Surface would give a very bad signal, so this is out of question. Windows RT must go on in order to encourage app development for the Windows Store.
But given the existence of the fairly successful Dell Venue 8 Pro / Lenovo Miix 2 / other fanless 8" tablets running full Windows 8.x, I am inclined to believe that Microsoft may launch two Surface Minis:
- One "Surface Mini" with ARM processor running Windows RT (launched solely for low-cost reasons and to give a signal that Windows RT is not dead yet).
- One "Surface Mini Pro" with Intel Moorefield x64 (next after Bay Trail Atom) processor, running full Windows.
I may be wrong, but I don't see why Microsoft would launch a Surface Pro 3 right now. They need to put Intel Broadwell in it (which is not available yet), and they can't launch another Haswell right now and another Broadwell in 6 months. But who knows.
But I think that companies like Dell and Lenovo are producing those devices with Windows 8 because they are not (yet?) on the RT bandwagon.
I was never interested in Surface with RT because I still own and use far too many legacy/Desktop apps to make the switch; however, I love the Touch UI of Windows 8 so much that every chance I get, I replace a legacy/Desktop app with a Windows 8 app. When I purchased the SP2, I kept my SP1 and now I use it when I head out for appointments, breakfast, etc., and I only need/make use of non-legacy/Desktop apps. This is when I started to think more about RT and how it could be of value to me.
When I jumped on the SP bandwagon, it was to replace my laptop and become my primary computing device. I use my SP2 at home connected to two external monitors and I also use it on my travels, alone, so screen size is important. As a result, I couldn't fathom using legacy/Desktop apps on an 8" device! Windows 8 apps, yes, but not legacy/Desktop apps--upon which I am still heavily dependent.
So it would completely surprise me if MS were to release a mini SP; to me, that small size is best served by touch-based apps only, not legacy/Desktop apps.