I think one of the big differences will be with the speakers. If they make the standard model require AirPods, they can eliminate speakers entirely and save significantly on cost.

Another possibility is moving from metal to plastic for the frame design. This saves on cost and weight. They could also take out the 3D camera.

I strongly believe they won’t compromise on the display resolution or the EyeSight feature, though it’s possible they’ll be able to fake the lenticular effect using software and opt for a simpler outward-facing display.