The big selling point with USB is backward compatibility and its standardization. Every computer made since the late 90s has some sort of USB port on it so its become an industry standard. The USB port isn't going anywhere anytime soon. Look at the VGA port with DVI/HDMI being superior to it, yet VGA still holds on as a legacy port since it is supported by older monitors that lack DVI/HDMI connections.

Newer graphic cards doesn't include a VGA port, however they put a DVI <-> VGA adapter in the box. Soon, they will stop putting it. That will be done to make a progress in the world's standards. You don't use a SCSI hard drive in your high end PC, yeah? Same thing here.

Thunderbolt depends on PC manufacturers - it's their wish to include a port in motherboards.

Thunderbolt will be a failure, but only for data. No existing drive would have such transfer speeds.

Here is a comparison (NIC Thunderbolt though)


SOURCE

Another test: You Tube VIDEO

I have not tried installing/running Win7 on a USB connected drive but have successfully tried a eSATA drive, the install is a bit tricky but it is added to the boot menu & does run quite well.