Manchester City for a fact has lost few of their players that helped the club win treble last season but that doesn't stop them from being the strongest English Premier League club at the moment.
After the departure of IIkay Gundogan, he was replaced with former Chelsea midfielder Mateo Kovacic and which I think is a perfect replacement and now that Riyad Mahrez is gone City still possess squad that's capable of winning as much as they won last season
Yes, for now we have seen a growing issue where Mahrez is likely to leave Manchester City and join Al-Ahli. Even in the progress of the transfer saga, it has been ensured that Al Ahli will get Mahrez in this transfer window. Even the position left by Mahrez doesn't really worry us because Grealish could play in that position if Guardiola wants him in that position. So I say that Manchester City still has a stock of quality players that keeps them from losing balance if their players leave in this transfer window.
However, Pep Guardiola is also worried that he will soon recruit the right replacement for the place left by Mahrez. Raphinha is the target of Pep Guardiola in this transfer window. I am sure he will be interested in joining Manchester City if Manchester City makes an offer for him.