I like that theory!
I remember watching a youtube vid on how folding a higher dimension will allow you to travel in the lower one. Like an ant on a piece of paper, fold the paper and he doesn't have to move as far. Same with a string as a one dimensional moving by folding in a two dimensional.
So not only would a 4 dim. being cast a 3d shadow, but if they folded the 4th dimension for us we could travel through time. Although maybe only into the future, unless they twisted it somehow.