Stephen Hawking is a brilliant man and deserves much credit for his work on black holes, Hawking radiation and the gravitational singularity theorem however I would not place him in the same Physics pedigree as Einstein.
Albert Einstein’s Special and General Relativity smashed the notion of absolute space and time and redefined how we understand mass energy, momentum, gravity as well as the simultaneity of events. In addition, he contributed immensely to Quantum Mechanics with his explanation of the Photoelectric Effect (for which he won a Nobel Prize) and was arguably one of the greatest conceptual thinkers who ever lived.
His boots will not be easy to fill and they perhaps may never be. Indeed even Hawking himself borrows immensely from this magnificent thinker who set down the groundwork for a vast amount of Modern Physics.