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...
A trophy in Champions League last season can be a good start for them to be recognized as a big club in Europe but they are far to be a best club or a dominating club in Champions League. They don't have such tremendous history like Real Madrid and they have yet won some Champions League in a row.
They can do it, starting from the last season, and will achieve it if they continue to succeed in Champions League next few years. We have to wait for their sustainable success in Champions League to conclude they are a dominating club in the last 5 years or 10 years. They have years to come to that recognition which is not easily to achieve.