I am actually not still clear on this, if pep guardiola is leaving Manchester city or he is staying, because it's already been speculated that he is leaving this summer, but if truly he is leaving, it's definitely going to reduce the dominance of Manchester city in the English premier league, but if he stays put, then I believe that the dominance of Manchester city will continue, because aside arsenal, I don't see any of the remaining team in the English premier league challenging Manchester city to the title.
If you look at Liverpool and Chelsea, they just recruited a new manager, so they will obviously needs time for them to instill their ideas into the minds of their players, and as for Manchester united, their is nothing special about them since sir Alex Ferguson left the club 12years ago, they are just struggling, so I believe that it's still going to be between Manchester city and Arsenal regardless of if pep guardiola leave or he stays.
Based on the news circulating, Pep Guardiola will leave Manchester City because he is either bored or wants to look for a new challenge. I don't know for sure because I forgot. but if that really happens, I think Manchester City will probably experience a change in performance, whether they will be better with their new coach or even worse because of the new coach who might come. not to mention the new coach, whether it will be suitable or not, the process of getting better takes time, so of course if they get a new coach they have to adapt to each other. but indeed, if Pep Guardiola stays, maybe Manchester City will still have a good performance in the English Premier League.
It is true that of course it takes time to instill ideas and of course they need a process to get to know each other or adapt. with Chelsea themselves, they reportedly can't be patient in this matter, so they can't find their best point in their performance even though I think Chelsea are currently showing progress, but maybe because they are impatient so they are looking for a new coach again. Whoever their coach is, they must be able to show their best performance for the competition next season.