Theo, isn't that what they did with Vista? They released a patch which they called Windows 7. Indeed, Vista was horrible but Windows 7 was OK. You may be too young to remember the same happening with Windows 3 and 3.1. Or 98 and 98 SE. History is bound to repeat itself.
Edit: I tried the update again and it worked. Turned out I did something wrong before the update, and now with 8.1, I find it a lot smoother and better than the 8 Pro...