That's not really true. Google's range of products is tiny compared to Microsoft's, and while Microsoft's quality is variable (partly due to their wide range) it's not the case that they're universally bad.
Microsoft rely on their closed source, Google rely on physically owning the servers their services rely on. Will you be able to run your own set of Google services on your own kit, or on a third-party VM host and retain the full functionality of Chrome OS? I doubt that somehow.
If it's anything like Android, it will be open enough (well, completely open, actually) that you can hack it to make it do what you want. You could hack it to work with Yahoo or Microsoft, or DedaSys, for that matter.
Well, OK, I have an old Mac SE/30 at home. It's a fine machine for basic word processing etc. I'm running Word 5.1 on it, how old is that? Yet despite it being closed source, Microsoft, utterly unsupported, yadda yadda, it works fine. In 20 years, will I be able to have my own completely independent Google Docs running on a Unix that doesn't exist yet, in a datacentre operated by a company that doesn't exist yet, and have all my old docs still there?
Basically, I don't think this has been very thought through.
Microsoft rely on their closed source, Google rely on physically owning the servers their services rely on. Will you be able to run your own set of Google services on your own kit, or on a third-party VM host and retain the full functionality of Chrome OS? I doubt that somehow.