I’m far FAR  from an expert on Hawking’s work and I have never claimed to be. I’m just one of the plebs who found his theories and life interesting …. but….

I think to answer what Hawking’s lasting legacy is one has to ask some questions.

Will his idea’s , theories, body of work be used by existing and future scientists to move things along ? Undoubtedly.

Did he bring Cosmology, Quantum Physics to the masses in terms they could grasp, therefore sparking future generations to question, learn and carry on these studies ? Undoubtedly.

That’s a pretty decent legacy in my book.