The USB Promoter Group’s announcement on USB 3.1 specification. Think 10Gbps.
SuperSpeed USB 10 Gbps uses a more efficient data encoding and will deliver more than twice the effective data through-put performance of existing SuperSpeed USB over enhanced, fully backward compatible USB connectors and cables.
Compare that to the upcoming Thunderbolt 2 specification. Ben Lovejoy:
Thunderbolt is technically superior to USB 3 – combining PCIe, DisplayPort and power signals into a single cable – and the recently announced Thunderbolt 2 version (which will debut in the new Mac Pro) doubles throughput to a blistering 20Gbps. And Thunderbolt can deliver that bandwidth to more than one device at a time.
The problem with Thunderbolt is the same as with FireWire. USB performance is good enough and costs much less.