There have been a number of attempts over the years to create a motion blur.

Some have used a alpha setting on the camera, but this tends to generate unwanted transparencies and so is not really an option, IMHO.

Another way is to render the view to an object just infront of the camera, which is slightly delayed, and semi transparent. With several of these you can create a pretty convincing blur effect.

What I would like to see, if a shader, that is either applied to an object to make it blur, or better still a shader applied to a model as above, that is just in front of the camera, that does the capture and re-skin method faster.