When he let go of Gundogan and Pep brought in Kovacic then he realised that it could be fulfilled. The doubts will definitely be there but Pep will always give his best and there is no way he would have brought Kovavic without some consideration.
Kovacic played very well for Croatia in Euro 2020 and World Cup 2022 so he is a useful player and has good experience. He has different skills than Gundogan so Pep will use Kovacic with different roles than ones he assigned to Gundogan. It is interesting to see how Pep will put Kovacic into his squad in a new season. I guess Kovacic will seriously focus on defense and with Kovacic, Pep will allow Rodri to play more attacking.
Right now they just have to focus on what they're going to do, Pep knows that there might be some adjustments with the new players in the empty squad but on the other hand he's always cool-headed and anticipates everything. I believe in Pep's choice although there are definitely some differences between Gundogan and Kovavic but of course we also have to see that Kovavic is not as bad as he looks and even in terms of experience and big competition he has got that not only at Chelsea but at Madrid and Inter Milan. So with the experience he has, of course I think Pep's choice will not be wrong.
We must mention one more thing, Manchester City did not spend too big cost to have Kovacic and the player will not too big pressure. With that cost, don't ask too much from Kovacic but I believe he will play well for them with all ability he has.