although several players have been confirmed to leave the Man City squad, their team does have enough good quality players to be consistent this season both in the domestic league and in the Champions League. but I feel that Man City's competitors in the Champions League are not Munich, they are still struggling up front. Man City's competitors might as well be from the Premier League. maybe Arsenal or United. these two teams are quite ready to compete this season.
We cannot yet give the fact that any team will be consistent in the Champion League group phase starting still long so I think it cannot be determined even though Manchester City is widely favored.
We never know how their game rotation will be in the future, of course every team has the desire to get the UCL trophy this is not easy and this is difficult to guess.
You said the other contenders aren't from other leagues apart from the English league, so what about Real Madrid and Barcelona? And teams from Serie A can't compete?