Back-to-back title is quite possible for Manchester City when we think about it on paper. Because technically they have one of the best squads in Europe now. And they are playing according to Guardiola's really solid system as well. However this task is still going to be quite difficult for them at the same time.
The reason why is that they have really challenging opponents such as Bayern Munich and Real Madrid. Manchester City won the title for the first time in their history previously. It would be really challenging to retain the title against these more experienced teams.
De Bruyne and Haaland are needed as a duo for Manchester City from now on to increase their chance.
Manchester City winning the Champions League trophy back-to-back this season is possible because Real Madrid and Bayern Munich are the real threats to Manchester City. Manchester City beat Real Madrid and Bayern Munich last season to reach the UEFA Champions League final, and Manchester City can still beat Real Madrid and Bayern Munich this season. The reason why is that they have really challenging opponents such as Bayern Munich and Real Madrid. Manchester City won the title for the first time in their history previously. It would be really challenging to retain the title against these more experienced teams.
De Bruyne and Haaland are needed as a duo for Manchester City from now on to increase their chance.De Bruyne can immediately return to his best performance but we still don't know about Haaland. So this season the UCL will probably be fiercer than last season. Unless Haaland returns and remains in good form then Man City's chance of winning the UCL title again could indeed happen again.
Inter Milan is also something to be reckoned with. Because this season Inter Milan also looks stronger than last season. And Serie A clubs are sometimes difficult to predict. And can always make other strong teams overwhelmed when facing them.