Man City are probably the best club in Europe right now, but don't forget how they only managed to push Arsenal out of first place at the end of last season... So there are strong clubs in the EPL now too... I think that next season Man City will not be as easy as last season and I don't rule out the possibility that they won't be able to win again...
If the top clubs in the EPL still maintain their old players and don't add or overhaul their team squad it might be a bit difficult to compete with Manchester City, so far Manchester City already has several quality players even though they have several players who have left but they are adding players new additions to complement the departed players so the team will remain solid.
Being a consistent club in defending titles is not easy, although I know for Manchester City it is not that difficult at the moment. But still, the ups and downs of challenge after challenge will complement each club's journey. With the club's spirit overhauling its squad proving they are serious about being a worthy contender next season. If you focus on the Premier League, there is no need to doubt the dominance of Manchester City, but the Champions League will be difficult to predict.