Would you even need anamorphic lenses if you shot digitally, or can the amamorphic distortion be done by the digital camera itself?The general rule is you photograph whatever you're filming in the best possible resolution. How that is accomplished with digital equipment depends on your target format of your piece and the format and resolution of the image capture device inside the camera. Whatever gives you the most pixels horizontally and vertically is preferable. Once the recording is inside the editing machine (computer), you can rescale (usually downscale) the image in any format you wish with little or no loss of resolution.
But as mentioned before, if you plan to add digital effects to your movie, you're better of working with non-anamorphic lenses regardless of the resolution just so that you can capture nice straight lines across the entire image. Anamorphic lenses normally can't record a scene totally "flat", often introducing curvature in all the straight edges. Merging digital effects to an image with curved edges is still too difficult to accomplish properly.