It looks like Microsoft will soon announce officialy support for USB 3.1 Type-C for Windows 10, with both the standard and USB Dual Role to be supported. The company will be hosting its WinHec conference next month, with the official website teasing the new USB connectivity scenarios in Windows 10 to be discussed.
The page says: "Windows 10 introduces support for USB Dual Role and Type-C, which will enable new wired connectivity scenarios such a phone interacting with USB peripherals, or laptops connecting to an external display using the USB Type-C connector. This session will go into detail on how Windows supports these technologies and what you need to do to enable them. Topics include: Overview of the new use cases introduced with USB Dual Role and Type-C, What scenarios are and aren't supported for Dual Role devices, Using Alternate Modes (e.g. DisplayPort, Thunderbolt, or MHL) over Type-C, Support for Power Delivery, enabling devices to provide/consume up to 100W over USB, Hardware and software architecture changes for Dual Role and Type-C, and Building a Windows system with Dual Role and/or Type-C support. Intended Audience: OEMs, ODMs, IDHs, IHVs, Peripheral Manufacturers, Driver Developers".
USB 3.1 will be delivering a huge increase in transfer speeds, right up to 10Gbps, up from the current ceiling of 5Gbps that USB 3.0 provides. Thunderbolt is still faster, but the adoption of USB 3.1 should hopefully be much higher.