https://www.pcgamer.com/oculus-shows-off-140-degree-fov-rift-prototype-with-moving-displays/

As Oculus's latest VR headset, the Oculus Go, began flying off the shelves this week, the company was busy revealing the next prototype of the Rift, and it makes a number of significant changes. The "Half Dome" headset looks very similar to the existing Rift, but offers a 140-degree field of view—up from around 100 on the current model—and displays that move towards or away from your eyes automatically to help you focus on objects. 

Oculus did not confirm whether the "varifocal" displays would require eye tracking, but head of product management Maria Fernandez Guajardo told Facebook's F8 developer conference that the headset will automatically "move the screens depending on what you're looking at". The alternative to eye tracking that I can think of is that the headset calculates what you're most likely to be looking at based on what's on screen.