Windows 365 could be a free or subscription-based Microsoft OS.
This is definitely "Welcome to RumorTown" territory, but Myce (formerly known as CDFreaks) supposedly has a genuine leaked Microsoft screenshot on its hands. The content of the screenshot, seen here, shows the Microsoft OS roadmap for the next 12 to 18 months.
The shot was sent into Myce by "Faikee," a known Windows/Microsoft information leaker. Seen in the screenshot are several Microsoft products, most of which have yet to be confirmed by the software giant.
Windows 8.1 Update 2 is listed, and it would be the next major 8.1 upgrade after the just-released Update 1. It's contents is still rumor at the moment, but it might include the return of the Start Menu.
Once Windows 8.1 is done with updates, we should expect Windows 9, which could be out as early as 2015. Even more interesting? The wording, specifically "Windows 9 & server & mobile edition," suggesting that the next version of Microsoft's OS will hit all devices at once. Office 2015 (also listed) would ship close to Windows 9 as well.
Last but not least? Windows 365, which...well, it could be a number of different things. It could be a free, watered-down version of Windows, or maybe it's slim subscription model OS (like Office 365). Personally, I hope it's a cloud version of Windows that can run on iOS or Android via an installed app.
Like I said up top, this is all rumor level for now, but hopefully we'll get more info on at least some of these products this summer.