Do you ever remember MS capitulating to whiners about UI changes in the past? Things like XP's "FisherPrice theme", the Office ribbon, stripping functionality from the defrag UI, etc were all whined about incessantly when they were released but MS stuck to their guns and kept them all as is and after some time people stopped whining and just got used to it. I'm betting MS does the same thing here.
Your thinking IMO is as wrongheaded as Ballmer and his legion of clueless executives on this. It's not a question of capitulating- it's a question of innovating.
Windows 8's Metro UI is not innovation. It's not essential to anyone's computing experience. There's a lot about it that's poorly conceived, poorly executed, breaks established usability guidelines, ,many users DO find it annoying to downright invasive, and so it must either have a lot more thought actually put into it, or dumped in favor of more modern and innovate ideas.
So if MS thinks they can just shove whatever crap down everyone's throat and everyone will just take it, they're mistaken. They'll eventually destroy the trust of the user base, become obsolete and drive more and more people away in favor of those who are willing to step up and offer innovation. Their mistake is in thinking they'll own the bully position forever, and though they are a long way from falling right now, it's not a guarantee that they'll forever be able to bully their way onto a majority of desktops regardless of what crap they put out.
You're also wrong that they haven't backtracked on many of their dreadful decisions over the years. The market has spoken loud and clear with other dumb or badly executed ideas of theirs: BoB, The Kin, their various failed mobile OS attempts, ME, etc. Despite some people's attempts to rewrite the history of it, Vista was a failure and prompted a return to much better design decisions with Windows 7 which is probably their biggest success.
It's the history of tech. There were huge computer corporations that dominated their industries when Microsoft and Apple were mere startups with 3 and 4 employees. Today most people couldn't tell you who any of those giants even were because the startups that were more innovative took over. The same fate will happen to Microsoft if it thinks it can always get by shoving poorly executed ideas in consumer's faces that are designed first to meet some corporate hoop-dream, and the needs of actual users a distant last. No, not overnight, but eventually such an attitude will catch up with them as it has many, many, many others before them who thought they were 'too big to fail'. There's really no such thing in business, and MS is no different despite any hype otherwise.