Scale path would be an interesting idea.
Edit:
Actually you can kind of do that now via image points.
If you add a bunch of image points to a sprite then arrange them like your track, and name them sequentially, all you would need to do is make a loop, clear the old path, scale the sprite, then do your loop again.
Add node at imagepoint(loopindex)... blah blah blah
Edit2:
Course you would have to come up with some way of tracking where you are on the path, and getting to the new position on the path.
An actual sale path would be a lot easier.