On the original topic, I am compelled to mention my 8 year old son. Without any forewarning he went from Windows 7 one day to Win 8 the next. He noticed the change and made mention of it but had absolutely no difficulty making the transition.
Granted, my son does have one advantage over Chris Pirillo's [stupid] father -- having not grown up in the Windows 95/XP era, he was accustomed to using the physical start button to toggle the start menu.
In my opinion, all of this hyperbole about Windows 8 being impossible to use is just that. It's bullshit.
Again, I am not saying everybody will or should like Windows 8. It IS in many ways a change of direction for the company; one that may jive well for people who have wholly bought into the cloud, and especially those likely to buy into multiple screens within Microsoft family (Xbox, RT, Win Phone 8 ).
While RT is going to remain a closed ecosystem, I don't believe the conventional desktop is at any risk of going away, the enterprise market is too important to MS.