You summarized it quite well and I think the threat from Galatasaray is bigger than some might think at the moment. The problem is not that Manchester United lost one game against Galatasaray, the problem is that they lost their home game against Galatasaray and for everybody who thinks that nothing is lost yet and Manchester United just has to show some quality and beat them in the game in Istanbul, those games are like hell with the Galatasaray fans backing their team. For Manchester United I think the game against Galatasaray will be no easier than the game against Bayern when they played in Munich. The atmosphere and then also the quality that Galatasaray has at the moment both makes me believe that Manchester United will not win that game. And if they don't win it I think they can't qualify for the next round in the Champions League.
Bayern Munich and Galatasaray won Manchester United, and the only club left is Copenhagen, which is completely out of the picture for anyone who underestimates any club at the moment because they have no comprehension of the fantastic performance that these teams will generate. The primary concern is, can Manchester United qualify from Group A after putting in so much effort and settling for less? I have enthusiasm for Manchester United since they are widely recognized for their capacity to turn things around in injury time, this is football were everything is possible to happen.
I don't think Manchester United can ever get out of the group in the Champions League. Yes, they are a team known for their comebacks, but they cannot provide stability. They had a plus with injured players and are currently struggling with losses in the group. In my opinion, even Coppenhagen is better in the group.
As for the Bayern Munich - Galatasaray match, it will be a very easy match for Bayern Munich, and they may even go the distance. Galatasaray's victory over Manchester United caught them at a bad time, but Bayer Munich is not like that, they are blowing like a storm this year, they also solved the striker problem. With Kane, they are undoubtedly the biggest favorites of the Champions League.