I don't think Manchester United have any chance of qualifying from this group anymore because their next game is Bayern Munich,and there is no way United can win Munich,if they cannot get a win against Galatasary or Copenhagen,then their hope is already lost.
There is always a chance for a surprise thing in football. We already saw many surprises happened in the previous seasons. So, it is not impossible if Man United can surprise us by defeating Bayern Munich and qualify for the next round. We know that Bayern Munich status is qualified for the next round, the last match isn't a very important match for them. So, Bayern Munich actually has no motivation anymore to play all out in the last match. This can be the chance for Man United to steal points.
Yes, you are right that surprises always come in football and no one can predict when the surprise will come because surprises come with luck.
But to say that Manchester United can give surprise and beat Bayern Munich to qualify for the last 16 is surprise that is very unlikely to happen, it is possible to win if they have that luck but to qualify then not.
Galatasaray and Copenhagen are still the determinants to qualify for the last 16 because they both have 5 points and they will meet in the last match, if one of them manages to win then it is clear that they have 8 points and can occupy second place to qualify.
Meanwhile, even though Manchester United won against Bayern Munich, they still won't be able to get second place because they only have 7 points.
The key to Manchester United success if they win against Bayern is that the Galatasaray vs Copenhagen match can be draw, this is an advantage because Manchester United can occupy second place with 7 points.
-snip- is it possible for Man United to beat Munich, which is said to be the strongest club in the UCL, that is clearly impossible unless Munich underestimates Man United too much and plays their second tier players to help make things easier.
I think it is not impossible although it seems a very small chance to beat Bayern Munich. However, if Bayern Munich uses their substituted players (second tier players) for the last match, I'm sure Man United has a chance to beat them. Moreover, the last match won't impact anything for Bayern Munich, they probably don't want to push themselves so hard in the last match.
And from this victory, at least if they fail to finish in second place, Manchester United can take third place to be able to play in the UEFA Europa League because when they finish in last place, Manchester United will not get anything and can only play in the English League for best competition they.
Moreover, even if Manchester United qualify for the last 16, it is not certain that they will be able to survive for long and will certainly fall more quickly before entering the last 8.