Now, Can We Consider Just Naming It TB3?
No longer will we need to fear the coming of SuperSpeed USB 20Gbps or any of the variety of rather confusing names which the USB-IF considered for the next generation of USB, in part thanks to Intel donating the Thunderbolt 3 protocol to the USB Promoters Group. USB4 will handle 40gb/s and will have TB3 baked into it automatically, and running at the same capacity. It will also handle power delivery differently, making it easier for devices to isolate it from data transfer. At this time it is now a specification(PDF), we shouldn’t expect to see it until later next year at the earliest.
This does give USB3.x a while to continue to grow and confuse even more people shopping for devices and motherboards.
The new standard also makes better use of USB-C's ability to be one-cable-fits all, splitting data transfer and power delivery in a way that's easier for the machine to differentiate, and allot power appropriately between multiple devices in the same port.