I personally won't be leaving the Microsoft platform, I have too much invested in it and frankly even with my gripes about the Windows 8 desktop I still prefer it to OSX or <insert distro> Linux. I do hope that some of the desktop usability issues are addressed though.
There are some very small changes and/or settings that could be added to change behavior that would appease a good majority of people upset (and then of course there will be some who will never be appeased). For instance, a "boot to the desktop" setting would be a warm welcome. Having a setting that allowed you to choose your start launcher (the traditional start menu vs. the start screen) would be welcome. Personally, I don't see this happening but I would like the ability to pull a Metro app out into a Window on my desktop (not snapped to a third of the screen but a Window). At that point, Metro apps become very appealing to me.