I guess he will leave because Lewa comes. He's an extreme tough guy and I like him very very much, among Kroos my favourite who I would always put on the field. But I guess he won't need the challenge because he's still a fighter and could fight with a bear and that's why he could leave. Here you can say "Fuck off Guardiola" . And there is the problem: Mandzukic has a very big head and wants his line. That's why we won the CL. He's much better than all the strikers in the past 6-8 years since Makaay. All the others can put the ball into the post but nobody has the fighting instinct that he had. No Gomez, Toni, Klose, Podolski...
Maybe it depends on how Pizarro will go on. For me he's a Bayern legend and he should get so many contracts as he want. But he's old and sitting the most time on the bench. He's already happy with that but maybe he's joining a club in Peru or somewhere else for his last year as a professional, so I guess: When Pizarro leaves, Mandzu stays, when Pizarro stays, Mandzu leaves. Just my thoughts but I'm very sure how it will go on ;) When then Pizarro leaves, some other semi level striker will join but that's in 1-2 years.
For me there is no need for Lewandowski but he's the best striker among Diego Costa in Europa at the moment so it would be fatal if Bayern let him go to another club... Real Madrid would have payed everything what he wants but I guess he's more a glory hunter and joins Bayern jsut because of trophies (CL...)