Gaurdiola will be able to revenge their last season defeat by Real Madrid, because it will be impossible for that to happen. Next season is the last season of Gaurdiola in Manchester City and it is not possible for City to win the champios league next season because Real Madrid is still super hot with the addition of Mbappe the team will be fire.
Pep will try his best to make the competition interesting but the king will remain being king. Next season will be a tough one in UCL and apart from Real Madrid we might see surprises from small clubs that we don't expect. This is why I don't think that City will reach the finals.
You are too confident that Guardiola will be able to take revenge on Madrid next season for their failure last season, although there is no guarantee that we will see them meet again, but despite all that, of course we will see a fierce and emotional match if indeed Madrid and Manchester City will meet again later, ahead of the new season of course there will be many improvements that will occur for both Manchester City and Madrid in the future, but in my opinion, if we look at the quality of Madrid players that has with Mbappe joining, of course it will be very difficult for Manchester city to be able to get their revenge next season.
I personally am quite sure that currently Manchester City and Madrid will still be the favorites next season even though we don't know who will win, but even so I hope that with the large number of Champions League participants next season, of course there will be surprises from other teams which is indeed capable of providing fierce resistance for the two teams later.