Haaland did a great job to make Manchester City win a title.
Haaland is a blessing for Manchester City obviously.
The squad is wonderful as a whole of course. But Haaland was like the missing piece of the puzzle and after him they are much stronger. Haaland is a goal machine before anything else. He was a little more normal this season though. 
But he still scored 27 goals in the Premier League.Like I said on some other thread, Haaland has a release clause at the same time. It is said to be worth 175 million pounds. Guardiola has worries about the situation so he wants Haaland's future at Manchester City to be secured. Let's see how things go but I believe he is staying now.
Haaland is indeed a beast in EPL games but he needs to clutch those important games of UCL , right ? He is still young and have a lot of time to improve on important games and I think Pep will make him a scoring machine in UCL as well so it's just a matter of time. It's also very important for Pep to remain a couple more years with City because if he leaves , I really don't see City to dominate EPL in the way they did it until now.
I also don't see Haaland staying at City for the rest of his career and Bayern Munchen will try to get him at some point for sure. He is destined to be there at some point.