At OsmoDevCon [Steve Markgraf] released osmo-fl2k, a tool which allows transmit-only SDR through cheap USB 3.0 to VGA adapters based on the Fresco Logic FL2000 chip.

Thunderbolt Gen 1 and 2 don’t support USB 3.1, Type C or even 3.0 for that matter. An adapter wouldn’t have fixed this problem. However, Apple is releasing Thunderbolt 3 later in 2015.