The Manchester City squad has been perfectly formed based on the success achieved last season, the departure of Ikay Gundogan will not have a major impact on Manchester City performance because there are still 10 other players who are very integrated with the philosophy used by Guardiola. Riyad Mahrez departure is not too worrying, he is not the first choice in Guardiola's squad, although Manchester City are not looking for a replacement for Riyad Mahrez it will not affect Manchester City appearance this season.
Guardiola will try to bring Manchester City back to the highest point in the UCL this season, his experience in managing strategies when busy schedules are needed to prevent his players from getting injured or exhausted due to being forced to play too often. Manchester City's potential in the UCL this season is still very large, they must support each other to advance to the final round, Guardiola tactics have also greatly supported Manchester City journey this season.
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.