I've also heard about the rumours regarding Cristiano Ronaldo to join Bayern Munich in this summer. However, I don't expect this to be more than a rumour in the coming days. Because I'm feeling like Ronaldo will decide to stay and play for Manchester United one more season. For Bayern Munich, it would be nice to bring Ronaldo to Lewandowski's place I guess. Their priority now is to keep Lewandowski of course. They have signed Mane also but I don't know if they are thinking him for that position in that situation.
CR7 is linked until now to Bayern to replace Lewandowski eventually, with Roma to play with his coach Mourinho, with Sporting or Chelsea and he rejected an offer to move to Miami.
Until now he will remain with ManU but everything could change at any moment if he gets a good offer imo.