That's all well and good, but the question was whether it supported actual Thunderbolt, to which the answer given was "yes" but the actual answer appears to be "no."
Supporting something like Thunderbolt is nice, but not exactly the same. It's not about "brand identity," it's about "does this equipment I have work with this machine?"
Just to clear up the FUD, the Type-C connector supports 'Alternate Modes.' This allows manufactures to implement chips that can MUX different signal types onto the USB cable SS lanes. There are 4 SS lanes that can be reassigned and either 2 or 5 additional wires that can also be used depending on if it's a cable or dock connection.
So, can the Type-C connector support Thunderbolt? Yes. Does the Type-C connector currently support Thunderbolt? No. Will someone add Thunderbolt over Type-C? Maybe.
I've only heard of PCIe over Type-C (via the spec docs) and DP over Type-C (from the VESA guys).
It certainly sounds like an excellent connector. If Apple can shoehorn Thunderbolt into that, it would be great. If they can't, it sounds like it's well worth it anyway.
That's hardly unique to this situation though. It doesn't support Firewire or eSATA or VGA or ethernet or AppleTalk or Centronics parallel either. Life moves on, and this is hardly a company gripped by concerns for backwards compatibility.
You seem to have confused "Is this the end of Thunderbolt as well?" with "I hate Apple forever for changing things." It's a simple question with a simple answer. (Yes.)
Life moves on, but Thunderbolt is such a new interface to be obsoleted.
They picked USB.
And thank goodness they did.
The "U" in USB may finally become reality. It's overdue.
Does this mean that Thunderstrike (and previous PCI-based attacks) are not usable against the new Mac?
No, there is no access to PCI address spaces over the USB 3 port. At least not yet, with existing hardware. As mentioned elsewhere in the thread it's not an impossibility to see an evolved (but compatible) standard in future USB 3 hardware.
And the USB 3.1 "SuperSpeed+" PHY is a 10Gbps thing that is very comparable to Thunderbolt electrically and would be expected to evolve similarly.
You're right that USB lacks the PCI framework (which many of us view as a feature). But DP/Thunderbolt similarly lacks a cabling standard with the sophistication of USB: no charging, not reversible connectors, no OTG-style switching of host/guest mode.
Apple had a choice of supporting both connectors, or giving up "PCI madness" or "nice cables" to get just one. They picked USB.