I guess nobody is or should be worried about scoring Goals for Bayern Munich without that Lewandowski not playing anymore there.
He scored only so much Goals because the other players have been set it up for him most times , also there was a lot of penalty goals he has done.
Bayern Munich has so much very good players that can score goals , and i guess we will see a lot from Mane in the future.
I think depending with your opinion not have to worry about who will scoring goal for Bayern Munich after leaving by Robert Lewandowski as dramatically opinion. Right now Bayern Munich have loss central forward and Sadio Mane arrived to Bayern Munich is not central forward position, he play as left winger with Liverpool and looks he not ever play as central forward position put by Jurgen Klopp. Really need replacement for Bayern Munich who will be top scorer actually really need central forward, with substitutes player like Choupo-Moting still not have good talented can replace position leaving by Lewadowski and less chance for him will get regular position with Bayern on next season.
I would have worried about Bayern Munich scoring if the competition in the Bundesliga for Bayern Munich had been higher. But obviously, the competition is not at the level of Bayern Munich. So I don't think they have to worry too much about anything at all.
Yes, it would be interesting to see Haller from Dortmund having a spirited race with someone from Bayern Munich. Nevertheless, it does not have to be a central forward. It can be Sadio Mane for all I care.
My point is Bayern Munich is nothing without Robert Lewandowski. Yes, Robert Lewandowski was the most valuable player at Bayern Munich. He has scored the most amount of goals as well. But him not being in the club only means that the club will be missing a lot of goals going forward. Not suddenly dropped from the top four positions.