At the World Conference on VR Industry in Nanchang, China today, HTC announced this new "Vive 6DoF Developer Kit" which includes a pair of 6DoF controllers, plus a tracking attachment that goes on top of the Vive Focus. Much like how developers can port their two-handed VR experiences to single-controller VR headsets via Vive Wave, this time they can even preserve two-handed controls thanks to this dev kit.
In a video clip provided by HTC's China President, Alvin Wang Graylin, the 6DoF controllers appear to respond well even with his wide range of movements -- he has incredibly long limbs -- in Beat Saber, though I would have liked to see him try a faster song just to push the hardware a little further.
For some reason, Graylin and his company are staying mum on how the 6DoF controller tracking works here. All we can see is the circular object on top of each controller, and the attachment gently bulges around a good part of the headset's main body -- likely for ensuring maximum coverage for tracking both controllers.
It's worth noting that since this is only a dev kit for Vive Wave developers, it's unclear whether consumers will eventually be able to make the same upgrade to their existing Vive Focus headsets. Even if that is the case, the commercial version may have a different design. Regardless, this is a good sign of what's to come for the Vive Focus and similar standalone 6DoF VR devices.