It blew my mind the other day when work gave us one of Apple's hdmi/usb/charge multiport adapters, that it could power 4k60 and a USB3 port without using thunderbolt under the hood. It was my understanding its either 4k60 with no usb, or 4k30 with usb. I'm assuming its using this newfangled HBR3 under the hood, or perhaps it actually is using thunderbolt secretly.