Hamilton, though, says he is not worried.
"When I decided to go to Mercedes," he is quoted by Brazil's Totalrace, "I had much greater reasons than just him.
"To me, that he was there was a bonus, but after I arrived, I saw that the team had a lot of talented people," added Hamilton, whose new team bosses will be Paddy Lowe and Toto Wolff, overseen by chairman Niki Lauda.
"He (Brawn) was a good boss, with a very good approach, which creates a great atmosphere in the team -- but this is something that is expected of a leader," Hamilton continued.
Brawn has resolved to take a sabbatical from F1, and says he will only decide if he will come back in 2015 in the summer.
But Hamilton, 28, said even a permanent exit from the sport for Brawn will not be a blow to F1.
"The sport will continue when any of us go," he said. "So no, I don't see it as a loss for the sport."