Okay, I didn’t know what deferred income meant. If you do I think the news will be clear, and boring. They’re talking about spreading the income already earned (from selling Windows 10 to OEMs) throughout the supported lifecycle for Windows 10 (until 2025).
This is a standard accounting practice when a large sum of money is paid up-front but the company is on the hook for providing future services. Nothing to do with future subscription fees.