Based on UEFA Champion League winner history there are not any teams yet success winning back to back except Real Madrid success win three time in a row, I doubt with Manchester City has chance for winning two time in a row for Champion League tittle. For next season, Manchester City leaves by Ikay Gundogan and Ryan Mahrez although the second name is not main squad for Manchester City but Ikay Gundogan is most important player with Champion League tittle contribution.
Achievement winning Champion League last season based on how smart tactic from Pep Guardiola, not depend on one player exactly when Erling Haaland get huge pressure still have player on second line for scoring goals. If Pep Guardiola tactic for next season still the same has chance for winning back UCL but its not easy.
Right now, talking about title race is too early even Manchester City is still one of the best to defend their title but as changes are happening around the clubs we can expect any serious challenger in coming days as well which can create problems for them like if we have Harry Kane in Bayern Munich then surely things could be not easy for any team to handle them and same case can go for the Real Madrid if they are able to bring Mbappé then surely their strength could be at the top, and they can go through for another title easily same happening for the few other teams which are working on their squads and fixing their holes which hurt them in last season.
Pep Guardiola is surely currently one of the best in business and his tactics are surely giving them good success but leaving top players surely can hurt their performance, and they can also face problems with we all know Champions League is never easy to predict its nature is always unpredictable.