I'd be very surprised if there's ever a varifocal for this camera. The varifocal control for both lenses would have to be so precise to keep both lenses perfectly aligned that I doubt it's either possible or if it is, economic to achieve. It would also have to be so good as not to suffer drift over time. I imagine these will probably always be fixed focal length because of the limitations of alignment. Pleased to be proven wrong though.
Agreed, I definitely see the Full Color 4K being a varifocal in time but this dual lens would be nigh on impossible to have 2 lenses aligned through a varifocal range. That and even if it was possible, would be more expensive.