I think it is not that much difficult given how Guardiola has managed City ever since he took over as manager. He has made then PL champions 5 times out of 7 seasons and that really shows the kind of spectacular record Guardiola hold rights now. I think in 8-9 seasons he can make them equal to United if things goes like this. City are in control in whichever way you see and despite United and Newcastle improving, I don't see them getting dominant the way City are right now. I would say its very much achievable if Guardiola says for long term.
I think Manchester City could perform as good as they did in the just concluded season and perhaps, go ahead to win the premier league title again next season. Pep has really done a lot to change the fortunes of the club and I believe that if he remains with the club, he could go ahead to win more premier league trophies as well as other trophies.
Thanks to Pep, I see Manchester City as a disciplined club that would remain dominant in their games come next season. I know It’s a bit still early to tell but Manchester City has a really good chance of retaining their title again next season.
So far I see that Manchester City is a consistent team under Pep Guardiola, even since the first time Pep Guardiola joined. So it's not wrong to say Manchester City will probably be a top contender in the Premier League next season with their very stable squad because they have the capital to do that. I can even say they are the best team right now in the Premier League or even in Europe.
From the squad they have, it's clear they have managed to build a solid foundation so that they can easily do something and when new players arrive they can adapt well, and that's because they have the foundation that Pep Guardiola managed to build.
With their success in winning the treble winner this season, I'm sure they will be even more motivated and want to achieve the same thing even more in the coming season.