Now let's imagine if Haaland gets injured who has contributed 36 goals what will happen to Manchester City still reliable? so this is where Manchester City's weakness problems like this can come at any time while Arsenal do not rely on one player they play their respective roles while on the field. I still have hope that Arsenal will be the strongest competitor for Manchester City so we won't see the dominance of just one team.
Manchester City didn't have Haaland in the other seasons although they finished first in EPL and played in advanced stages in Champions League. The strategy will certainly change depending on the games and what Guardiola feels appreciate, they will figure a way to adapt.
The advantage of having Haaland is playing comfortably in the hardest matches while stressing the opponents a lot. His firepower guarantee the success of the team whenever he is fit for the game.
I would say Guardiola's brilliant match strategy is why Manchester City won the Premier League and Champions League titles. There is no doubt that Haaland is a very important player in City's squad. But it would be wrong to think that City won the title only because of Haaland. Manchester City's squad is very stable. And Manchester City is strong as a team. They weren't solely dependent on Haaland's performance. Guardiola changes his match strategy before various important matches. This is why City's performance was consistent throughout the season.