I can say currently Manchester City is the only team we know they can have hope for the next Champions League title with Pep Guardiola because they are still in good form and they could stay stable and keep the main players they need for the next season. Also, Guardiola is improving the team and we can see even stronger Manchester City in the next Champions League season.
In theory, Man City should be the favorite team to win the next UCL title because they have strongest squad and keep most of their main players in the last season. Moreover, Guardiola is still the coach of Man City, he knows well how to manage Man City properly. I can agree with this opinion, but there is no guarantee that Man City will be the champion again. Some teams may decrease their performance after they won the title, it isn't impossible to happen with Man City. The other teams are also improving their squads, they can be stronger in the next season. So, the competition for the title can be more difficult in the next season, Man City shouldn't be too confident to win the UCL title anymore.