Most of them are USB-C docks, which are different (and much slower) than the true Thunderbolt 3 docks, which can reach up to 40 gb throughput rate.
The only true Thunderbolt 3 docks I know of are upcoming ones from Belkin and OWC.
This is an interesting point I hadn't considered. My throughput needs are pretty modest – AV output to fairly basic projectors and external monitors, backup to Time Machine (only large-volume BU initial transfer), mostly moving around files no larger than a few 100 MBs. Any cases were true Thunderbolt 3 power would really help my usual workflow?
For my upcoming MBP 13 touch (85% sure I'll pull the trigger) I was planning to just get 3 sets (home/office/road) of USB-C dongles/hubs to stay connected. Tentative strategy:
Home – recycle USB-A Ethernet cable with a basic adapter (e.g.
this one); hook up my aging but dependable Samsung monitor with a dvi converter (e.g.
this one); above basic adapters for USB-A external hard drives for backup/storage and charging/syncing iPhone 5s; Apple stock charger that comes with MBP for power
Office – an all-in-one number (like
this one on Japan Amazon or
this one) for HDMI monitor connection, USB-A needs, Ethernet; this
3rd party charger for power
Road – again, a recycled Ethernet cable with adapter; an adapter
like this one for VGA and HDMI projectors/displays, the two types of interfaces I can expect at Japanese universities, conference centers, company offices, etc., as well as for USB-A use; above 3rd party charger for power (although
this pricey baby is quite svelte)
Any significant holes in that strategy?