The USB Implementers Forum (USB-IF) today published the official USB4 specification, which is based on Thunderbolt 3.
“The USB4 specification is a major update to deliver the next-generation USB architecture that complements and builds upon the existing USB 3.2 and USB 2.0 architectures,” the organization announced. “The USB4 architecture is based on the Thunderbolt protocol specification recently contributed by Intel Corporation to the USB Promoter Group. It doubles the maximum aggregate bandwidth of USB and enables multiple simultaneous data and display protocols.”
To be clear, this is a good thing: Thunderbolt 3 functionality has been available via USB-C for several years now, but adoption has been spotty, with some PC makers mixing and matching between traditional USB-C ports and more powerful USB-C/Thunderbolt 3 ports. (Only one PC maker, Microsoft, has completely ignored Thunderbolt 3 for some reason.)
So what USB4 will provide is what we see today via USB-C/Thunderbolt 3 ports, a single, reversible connector that can deliver power, display, storage, and peripheral connectivity at speeds of up to 40 Gbps. It will be backward compatible with USB 2.0, USB 3.2, and Thunderbolt 3, too.
You can expect new PCs based on USB4 to begin appearing in the market as soon as early 2020. With the obvious exception of Microsoft, of course.