Harvin is expected to be out of action for a while having undergone surgery on a hip injury, while Rice was forced to leave the Seahawks' training camp to receive treatment on his knee on Friday.
The injuries could see Golden Tate return to the side for the start of the season, but Largent believes that the 24-year-old does not pose the same threat as Harvin or Rice.
"[Golden Tate] is a small receiver. He's a better third or fourth receiver than a starting receiver, I think, but he's got everything it takes to play," said Pro Football Hall of Famer Largent.
"He's made some big catches in clutch games, so he can play. But it will hurt badly if they're missing Percy Harvin and Sidney Rice."
Largent scored 100 touchdowns for the Seahawks and was named in the NFL Team of the Decade for the 1980s.