Neuer's absence would be a big hit to Bayern Munich actually. Maybe his absence wouldn't change much thing in the Bundesliga. But I don't think the same when it comes to the Champions League. Because they are already going to face one of the biggest title contenders like PSG. They need to stay as strong as possible in defense just as offense. PSG have the best trio in the world in their attacking line. They wouldn't forgive weaknesses in Bayern Munich defense that easy.
Mane is also a candidate to miss the first leg at least. It feels like PSG are becoming more favourite slowly.
It is time for Bayern Munich to look for a new goalkeeper to replace Manuel Nuer. Because he is no longer a young goalkeeper, age will be an unavoidable problem. I see Bayern Munich also starting to entrust Sven Ulreich. But they need to start putting more faith in playing time now even if Manuel Nuer is not currently injured. This is an opportunity for them to really be able to find a new goalkeeper.