I don't think that Bayern will have both Haaland and Lewa at the same time.
Lewa will surely get some good offers in the coming transfer window as I heard that Man City are interested in him. So, if he gets a better deal than what he's getting at Bayern right now, he might accept that and Haaland could also be a huge replacement for Lewa. And at the end of the day, Bayern have the trend to buy Dortmund's star players.
I also doubt that they would bring in Haaland. Obviously who wouldn't want Haaland but given the teams that are after him and the price tag he has and to mention his high agent fee , I hardly think Bayern will be interested in it. They might have thought about it but those thoughts wouldn't have made it further. Bayern CEO Oliver Kahn last year said that transfers beyond 100 million marks is unthinkable for them then but maybe situation has improved in one year but I still don't think they are able to keep up with the cost of bringing Haaland.