TB3 is already incredibly more popular than TB2 ever was. Even mid grade generic PCs are shipping with TB3 now, meanwhile even high end PC's did not come with TB2. Thanks mostly due to the common connector (USB-C).
And now even peripherals that utilize TB are able to make that step we've all been waiting for (especially with Apples implementation connecting directly to the CPU to minimize overhead, good on them btw). Very high res displays and eGPU's are most notable and will push TB into the mainstream.
USB will always rule the roost merely due to the amount of devices that don't need TB3 tech. However in the not so distant future those devices will more than likely be plugged into a USB C thunderbolt port that carries the USB standard of the time.