It's not Xbox, they're losing that war, and it was based on Windows. It's not phones, they already lost that one and that was based on Windows anyways.
It can't be Office; there's less and less of a need for a paid office suite, and MS Office in a browser is rather bad.
It might be Azure, but IMHO the big onramp to Azure is Microsoft pushing corporations to move ActiveDirectory and Exchange into the cloud, but the end of Windows means the end of ActiveDirectory, and there's options for Cloud mail and calendar. Is Azure compelling for many if you're not already there because of Exchange?
> And once you realize that you can see the future is very bright
The future may be bright, but how will you know if there's no Windows to see it through? ;p