USB 3.1 is available on the latest generation motherboards.
The USB-IF (USB 3.1) controller uses 4 PCIe Gen3 lanes and has a total bandwidth of 32Gb/Sec.
That's a lot of bandwidth for external peripherals.
Thunderbolt 2 offers 20Gb/Sec bandwidth.
Thunderbolt 3 offers 40Gb/Sec bandwidth.
Apple is pushing Thunderbolt 2 hard... because Thunderbolt 2 is absolutely critical for Mac users.
Current generation Macbook/Pro, iMac, and Mac Pro Cylinders have no other means of accessing the PCIe bus.
I mentioned this in another thread...
If you're feeling left out of the Thunderbolt loop/excitement, checkout the cost of some Thunderbolt peripherals.
- A 1TB Thunderbolt HD is ~$200.
- An empty Thunderbolt 1 bay (holds 2 or 3 drives - no drives included) is $300.
I've got 9 SSDs/HDs attached to my current machine. That would cost double/triple to duplicate via Thunderbolt.
Most audio interfaces are nowhere near saturating the USB 2 bus.
IMO, This is why you're not seeing mass movement to USB 3 and USB 3.1.
Simply adding more (unused) bandwidth to the situation won't increase performance.
Liken the situation to your car. Say its top speed is 120mph.
Doesn't matter if you're on a two lane highway or an eight lane freeway... your top speed is 120mph.
Adding more lanes (bandwidth) won't increase performance.
It'll be interesting to see how things shake out.
Out of the few USB3 audio interfaces that currently exist... none have equaled (let alone bested) the best USB2 units when it comes to round-trip latency. The Apollo Twin Duo is doing pretty well... but not quite as low as RME/MOTU.