The first thing a power user will do is to go to the old-desktop and stay there, basically not interacting with metro at all. There is no point, it's about as useful as the winkey+tab is on Vista/W7. "Cool" but useless for real work.
And there seems to have been numerous improvements to the windows experience (outside metro), the ability to pause file-copying etc. proves that they still have some focus for the enthusiast.
For everyone but the average Joe the new "metro-UI" is nothing but a bundled application that you will only use when you want to demo something or for some very light use (on a tablet for instance).
Just as Media Center is today!
How does a bundled application make the whole windows experience clumsier? If it is clumsy, close it! Sure, the start menu is different but who uses the start meny on windows today? All apps that you actually use are pinned to the task bar...
And that is how everyone that does real work will use their windows 8 machine, just as they do today in windows 7. And no. MS will not phase out the "regular windows", that's just moronic. Contrary to popular belief but people will actually do work in the near future as well, not floating around in a fluffy cloud with touch devices.
You read it here first. The mouse and keyboard are not dead.
Curious to see how broken the metro is on a multi-monitor setup is though. Any UI that doesn't scale well to multiple monitors has failed miserably in my eyes (hello OS X + Unity + Metro(?)). And that's not an edge case (at least it shouldn't be for anyone favoring productivity).