This is what you have seen with bats. They have legs within their wings. This is an interesting structure and consideration for a robot that we hardly think about. UAVs are usually developed for flight and with this approach the robot will be able to move around it’s environment in more ways than one.
This reminds me of RHex from Boston Dynamics. RHex is able to overcome almost all forms of terrain. Imagine with the ability to fly, RHex will be able to overcome more terrains and handle more situations. This certainly has use but it’s up to our imagination.