I do not see Pep at City long-term despite having nearly the ideal situation. Manchester is a far cry from Barcelona which is his home & country in Catalunya but City also lacks youth football setup in England (Reserves vs a Segunda like in Spain) despite having made great investments in their own academy. You can't really count too much on the youth players, look how long it took Foden and he is a standout gem - not sure you will see another player like him coming out of there anytime soon. They are more likely to part like Jadon, Angelino, Brahim, Garcia, Bernabe (He's also on an expiring contract) et al.
I think the long-term danger for City or their fans is the oil money leaving (Similarly, there is an undercurrent of talk of that with the Qataris and PSG after the WC). But coaching wise & in terms of academy, they are at their peak - it will never be better than this which means that the final product can only diminish in quality once someone as key as Pep leaves. It will have a cascading effect
Now should the club remain profitable, it can still be a viable project for the sheikhs but it may more closely resemble Chelsea as a football club in terms of coaching, management/operations and sporting success