With this tool you will be able to modify sprites.
It uses MeshFilter with MeshRenderer as base.
There are some information
Asset Store
Important. Point animation by “Sprite deformer animation” doesn’t work on Windows Store application because Unity have a bug with animating “struct”. It will be fixed coming soon.
I don’t have skill to write a good description 
so If you have any questions just ask me.
I created the demo version of this tool.The demo version was not included all source code, there is DLL. A build was created with the demo version would work only five minutes.
Download unitypackage
Sprite deformer tool is update.
There was added a lot of fixes and blend shape animation.
This is really interesting and I’m surprised no one has replied yet. You have to manually place the points from which the sprite will be deformed, correct?
Yes, you have to make a topology from edges and points on the sprite before you are be able to deform this sprite.
It just puts a sprite on the Mesh as UV and you can move the point of it, like moving a vertex at 3d soft.
It is a very manul tool.
Simple video: