According to a Russian leaker, the next version of Windows will be a free, cloud-based OS known as Windows Cloud. Windows Cloud would require an Internet connection for full functionality of the OS, but to receive functions past the basic ones provided for free, a subscription would be required.
The person behind the leak, Wzor, has been right on previous rumors, such as an early version of the Windows 8.1 update. According to PC World, part of Windows Cloud would be stored locally on your computer, possibly sitting in your PC's BIOS, with the rest of it downloaded from the Internet. When not connected to the Internet, it would offer the user just basic functionality.
This would work similar to how Windows 7 Starter gave users basic functionality, with the option to upgrade to other versions of Windows.