I think it will be difficult for Manchester United to allow a talented striker to leave the team at this moment where Manchester United got a new manager. Cristiano Ronaldo has many strategies to demonstrate in next season to make Manchester United fans happy because this season performance was very poor for their like which next season will be more better than this season. I think Bayern Munich will allow Lewandowski to finish next season since they have signed in mane the formal Liverpool striker which will really help the team to perform well in next season.
Even we have no official statement from Manchester United or Cristiano Ronaldo about any transfer or talk but still too much talk are happening about this topic in social media which is mostly unusual because most chances he is going to stay here for another season, and then we can expect something about his future even now Manchester United is not in Champions League but still it's good to stay here and play for their rebuild team which can bring some good results for fans in the future.
With after factor which is also having big impact, he needs to stay here and enjoy his rest of career because this can bring better memories for him and can bring positive change because money is never been for everyone like we have news from many players.