Without Kevin De Bruyne, it is very difficult to keep the performance stable. But it is not impossible. Last season we saw consistent good performances from City.
That's true without Kevin De Bruyne Manchester City will find it very difficult to perform very well although not because the Kevin De Bruyne is the most skillful player in Manchester City but however the role he plays on Manchester city is so important that the team can easily get affected by his absent.
Although I heard his injury may last for three months, who knows if he will be able to recover before there next two to three matches, but however irrespective of the absent of Kevin De Bruyne, Manchester city remains a serious rival to all clubs, and also with the kind of coach they have in the person of Pep Guardiola after seeing what happened on there last match against Arsenal he will never allow such mistake again, by making sure the team remains inform.