According to Sam Kasan of Pens Inside Scoop, Riley Sheahan was skating with Pittsburgh's second line in place of Malkin ahead of Sunday's Stanley Cup playoff matchup.
Malkin's importance to the Penguins largely goes without saying. He registered 98 points (42 goals, 56 assists) during the regular season, which were first on the team and fourth-most in the NHL.
Pittsburgh still has Sidney Crosby, which obviously helps soften the blow of losing Malkin. Crosby has been particularly effective in the postseason, scoring five goals and assisting on five more. Jake Guentzel has played well, having recorded eight points in the Penguins' first five games.
As long as Malkin's injury doesn't continue to linger for the Penguins, it shouldn't present a major problem to the team.