I looked at my USB 3 topography, and I have 4 USB 3 Hubs, and 4 USB 3 external 2.5 drives, with a few USB 3 flash drives, outside of those nothing else is USB 3. Everything connected to my USB 3 Hubs are all USB 2 devices, a printer, dongles, Logitech Camera, icicle Mic, etc. Nothing except storage devices is USB 3. I think this whole Type-C thing is just way over blown.
The only thing I could think of that was really cool was, the fact you'll most likely be able to use any battery pack with a USB Power out and connect a USB to Type-C connector and charge. THAT'S COOL!
But what else is there, I have thunderbolt dongles for monitors and thunderbolt external drives.
I wouldn't be surprised if Type-C, seeing as how the only connectivity will be Displays, Drives (RAIDs), Phones, and Power, that Thunderbolt 3 just overcomes USB. I mean of those mentioned categories, all but the the Phones would or could be TB3.
There just is no new USB3 type-c devices coming, I guess drives right, but if you had a drive, do thunderbolt? Unless of course confusion with Type-C ports arises where some Type-C is missing Thunderbolt 3, weird.
On an aside note, I did some testing on a USB3 Flash Drive, since I got my New rMBP 15/2015, pretty good results for an always plugged in USB3 flash drive giving an extra 128 GB, added to 256 GB SSD inside:
I love my retina 2015, but I am still so going to get Canon/Coffee, wish you guys the best of luck. I know you'll love your 2016s!