Hemingway said that one goes broke "gradually, then suddenly." I hope the same thing is happening to Windows marketshare. I hope the same thing is happening to iOS. edit: Note that I said "marketshare." I'm not wishing bankruptcy on Apple and Microsoft. It would be a weird desire.
If we have to have corporate oversight to get a decent OS, then I'd rather one I pay (e.g. Apple for iOS) than one I don't (e.g. Google for Android/Chrome OS). I want to be the customer, not the product being sold. Even if that's not what you want, choice is still a good thing: without choice, we have vendor lock-in and stagnation of ideas. To pick an example, I think the mobile ecosystem would be a lot better right…
For branded Android/ChromeOS, AFAIK, you are paying Google for it the same way you pay for prebundled Windows. Insofar as the OS cost is discounted because you are an advertising target for Google, that's not that different from Windows PCs where the OS cost is offset because you are crapware target for third-party business partners of the system vendor.
And advertising revenue, isn't, I think, the only motivation for the low cost of consumer ChromeOS; low-cost consumer ChromeOS is the lever for building acceptance, knowledge base, and build a base of apps to motivate institutional sales of ChromeOS (sort of the way that getting Apple computers into schools was always a way to build commercial consumer and business markets for them.)