I agree with you. Although the situation is getting difficult for Man United but the chance isn't over yet. Winning against Bayern Munich isn't impossible if Bayern Munich won't play with their main players and with serious efforts. Bayern Munich possibly use their second tier players because they already qualified for the next round. I think Bayern Munich will prefer to let their main players to take a rest. Meanwhile for the match Copenhagen vs Galatasaray, it is difficult to predict the result of the match. But it is surely not impossible to end with a draw. If both teams play all out, a draw can be the reasonable result.
Yes, it's not over for Manchester United, but what is the percentage for Manchester United to beat Bayern Munich to open up a chance of qualifying? I think it's very small even though they can win against Bayern Munich but their fate will still be determined by the result of the Copenhagen vs Galatasaray match, so Manchester United fans have to be realistic and accept if they are eliminated and that would be good so they can focus more on the English Premier League.
There is no other way for Manchester United other than to win the last match of the group stage which will be played at Old Trafford. Bayern Munich, which has been confirmed as group winners, will not take risks in this match, perhaps Tuchel will field a second layer of squad to give the reserve players a chance to play while also resting the main players who have always played in different competitions.
If Thomas Tuchel uses substitute players at Old Trafford, Manchester United must take advantage of the opportunity to add three points. Victory will open up opportunities for Manchester United to accompany Bayern Munich to the round of 16 if the other match between Copenhagen vs Galatasaray is a draw.