There is no doubt that Pep Guardiola always has a backup plan in managing the club.
And I think even now in the transfer market Pep Guardiola will definitely pick and bring in good players. because he always has a keen eye on players who have potential.
for now there are at least 4 players who are rumored to be coming to Man City Mateo Kovacic, Raphael Gurreiro, Kieran Tierney and Josko Gvardiol.
You named four players but I only see Gvardiol is a promising player who can be a target of Manchester City in the summer. That young player had a successful World Cup 2022 with Croatia and rumor that he was in transfer radar of Manchester City since the World Cup 2022 already. He is a type of Pep's favorite defender who can play defensive proactively and can contribute very well for attacking.
Gvardiol might indeed be a great player and there's no doubt he can strengthen Man City and suit Man City's game. but other names like Raphael Gurreiro are equally great players. In fact, he can always play his role well when he is played at the back or in the midfield. and to replace Gundogan who is said to be leaving Man City, the suitable player to replace him I think is Kovacic. Kovacic also seems to have agreed to sign for Man City and that means he will leave Chelsea. And I think Chelsea should be able to keep a great player like Kovacic more. But maybe Kovacic himself is not interested in staying longer at Chelsea.