The import aspect feels irrelevant, unless I'm missing something. Its not clear to me what you are asking, what is the difference...
You can already morph between two paths, assuming you can draw a rect or a circle etc as a path.
Lets say you have one large rect with 12 points.
You have a circle made via 12 points.
You want to morph between the two, then you animate the rect by passing it the path of the circle to animate to (ie the 'd' attribute which holds the path).
So the principle is the same, but I'm guessing you mean something else, but I'm not quite understanding that.
This is assuming the shapes are pretty straightforward, if one has a rotation applied to it, I would assume to animate between them, it would go a bit odd.
If you wanted to interpolate lots of aspects of 2 different images, I started something ages ago which I never finished, but could be of use to look through...
That takes different SVG images, loads them in, and tries to interpolate relevant attributes between each one in the frame, but its quite complex.