As spotted at the WEMU RC ScaleShop site in Switzerland, these pics show the prototype scaler that Traxxas is showing (leaking is more like it) at the Nuremberg show.
Portal axles! Note how the axles step down to reach the center of the wheels. More ground clearance, and greater gear reduction.
Note three mini-servos on chassis. Two are for locking the front and rear diffs, like Summit. The third is a high-low shifter? Or a center diff? Most likely high-low. XL-5 looks standard, but will probably get different programming–unlikely Traxxas would build a rig this trick and not set up the speed control with a crawler-strength drag brake.