I think many of us will start to change our tunes once we see it used to its fullest.  I certainly don't think the desktop is going to go away.  I already tested my company's main app on the preview (which runs in IE with about 15 activex, .net 2 and MSVC pieces) and it doesn't run in Metro IE period.  That being said, it is fairly easy to tab to the desktop and launch whatever you need, and I don't even have a touch computer.  So, even at worst-case scenario (and metro is it for good), it is still useable.  The point is imagining what we can put there to help people in their daily workflows.  

I can imagine business centric KPI/reporting services apps/reports having a nice refreshing Tile to keep people in the know.  That's just the beginning.  The point is to start to rethink the way you make apps too.  It's not just a gui.  Like I said, I think once we see it used in the right way, using all its potential, it will be easier to see how this "rethinking" of windows is really just that.  Of course they couldn't take our desktops away, so they did the next best thing (allowed both).