[UPDATE: Tobii confirmed after the fact that it is indeed their tech powering the Vive Pro Eye.] Regardless, you'll be able to both navigate the headset and VR experiences with eye-tracking. The headset doesn't need external sensors, yet can still provide full-range controller tracking.
Eye tracking capability within virtual reality headsets allows for a similar technique that follows the same principles as your eyes. The integrated eye tracking on the Vive Pro Eye gives users new levels of accessibility, including gaze-oriented menu navigation and removing the need for controllers.
The Vive Pro Eye, a revised version of the Vive Pro, is equipped with eye-tracking hardware.
The MLB, for example, has used the Vive Pro Eye for its Home Run Derby VR game. One of them is targeted at Pro users, and the other can be completely PC-free. In addition to the two front-facing cameras, there's also a pair of side-facing cameras, but HTC hasn't disclosed their functions.
Another big piece of the VR is all the software supporting it.
However, no other specifications have been released and no pricing or availability has been mentioned as yet.
When will the Vive Cosmos be released? Details are quite thin on the ground right now.
However, what we do know is that it will be a step up from the Viveport VR games subscription. Where eye's look and how they behave are intrinsic parts of everyday communication, enabling you to understand if someone is happy, sad, or if they're lying to you. "Now with Viveport Infinity, we're offering our members the best value in VR content with 100-times more choice, all at one low price".
Today, at CES 2019, HTC took the stage to launch several new products and upgrades in its popular Vive virtual reality division.
The Vive Cosmos is described as a "new premium PC VR system, and a vision of the virtual future". It announced a new VivePort Infinity plan, which it says is the world's first "infinite VR subscription".
Sadly, requests for more details about the Cosmos were met with a response along the lines of "We're not talking about that at this time", so hopefully we'll get more info later this year when dev kits start to go out "sometime in early 2019".