Currently, Manchester City doesn't have any competition in the Premier League. That didn't relax after their triple trophies. They are still buying more quality players so that the team will maintain its quality. I have not seen any club that is prepared for next season like City. There is also a sense of good relationship between the club owners and Pepe Guardiola because he always gets what he wants.
I think it is safe to say that Pep Guardiola knows how to win the Premier League, and that's very scary for the rest of the teams in the league, look at how many EPL titles he has won since he became manager at City, some he won on the final day, some with just a point, it doesn't matter, he just knows how to win it. Last season was their third title in a row, if they win it next season, they'll create a new record and become the first team to win the EPL four times consecutively, but who is to say they can't do it, which team is going to stop City, personally i can't see any. Pep is prolly going to turn the EPL into a farmers' league.
That is what makes it scary, that he wins those titles often times in a way however it is needed. When you look at the last season it was "only" 5 points between Manchester City and Arsenal, but I think it was only 5 points because Guardiola knew that it is enough. The scary thing about his team is that it looks as if they could play even harder if needed. If Arsenal would have finished the season with 90 points, Manchester City would have won one more game. They lost one and tied one game out of their last two games. But I am sure that would not have happened if they still needed to score more points.