Today, Intel announced that it's contributing the Thunderbolt 3 protocol spec to the USB Promoter Group, and with that, the USB Promoter Group announced the USB 4.0 spec. USB 4.0 will support data transfer speeds of up to 40Gbps, just like Thunderbolt 3.
The new spec is backward compatible with USB 3.2, USB 2.0, and Thunderbolt 3. Remember, USB 3.0 and USB 3.1 are now called USB 3.2, with USB 3.0 being USB 3.2 Gen 1 (also formerly USB 3.1 Gen 1), USB 3.1 Gen 1 is now being called USB 3.2 Gen 2, and then there's USB 3.2 Gen 2x2 for 20Gbps speeds. It will use existing USB Type-C cables for two-lane operations or Thunderbolt 3 cables for 40Gbps speeds.
“The primary goal of USB is to deliver the best user experience combining data, display and power delivery over a user-friendly and robust cable and connector solution,” said Brad Saunders, USB Promoter Group Chairman. “The USB4 solution specifically tailors bus operation to further enhance this experience by optimizing the blend of data and display over a single connection and enabling the further doubling of performance.”
USB 4.0 is currently targeted at developers, and the final spec hasn't been released. As we come closer to that, likely in the middle of this year, branding and marketing guidelines will be shown.