When they got Office 2010, they complained about the new ribbon for 10 minutes until they started to get used to it. I think we're overestimating the "nightmare scenario".
I've still hear Ribbon complaints and we upgraded to 2007 when it came out which has been a good amount of time. What I notice with that is people who were younger didn't seem to mind as much as they'd spent less time using Office. People who had been using office for 12+ years with the menus were far more likely to be disgruntled by what seems to them to be change for changes sake. Another thing that I've noticed is that these users are less likely to complain about "The Ribbon" when it comes in a new application that they've never used before.
This tells me that The Ribbon isn't bad, and people do like it but not when they're forced to re-learn 10 years of knowing where something is with no real gain.