FWIW, I wouldn't get too caught up in bus-powered audio interfaces.

If you use phantom powered condenser mics, bus-powered units often don't deliver enough voltage for maximum fidelity. Always use dedicated power if available.
USB and Firewire bus-powered audio interfaces have been available for a long while...
I'd use dedicated power with this also (for same reason)
Thunderbolt 3 literally just came out.
At this moment, few (if any) Thunderbolt-3 specific peripherals are actually available.
All the Thunderbolt audio interfaces you see are Thunderbolt-2.
With a single peripheral, it's somewhat a moot point if it's Thunderbolt 1, 2 or 3.
ie: A conventional HD sustains say 180MB/Sec. Thunderbolt-1 has plenty of bandwidth to accomodate.
If you have a PC with Thunderbolt-3, it's using a USB-C port.
You would absolutely need a USB-C to Thunderbolt-2 (often just called Thunderbolt) adapter.