Pep has a serious challenge ahead of him and how big that challenge is will depend on how much money city is willing to spend. A 150 mill transfer budget wont do much to make this a Pep style team especially if he tries to go for established superstars like Pogba, Neymar etc.
Lets assume the defense and Gk positions are fine and need no reinforcement. What needs major investment is the midfield and the attack. Silva and de bruyne can play tiki taka and fernandinho maybe but that is about it. So they need at least one CM.
Now wingers. Sterling lacks the brains, passing and finishing to be Pep's pedro let alone Robben or Ribery or Costa. He'd probably need to rotate on the wings with someone. Moreover, Navas is terrible. So city needs to buy two wingers (one for each side perhaps) and to keep sterling and nasri.
Strikers. Bony is terrible so he is out. Aguero is injury prone and is just one player so they will need at least one more striker.
So at the very least they need a CM, 2 wingers, 1 striker. With Navas and Bony sold which would get them 40 mill combined at best. If that sales money is invested in a winger then they would still need to buy 1 CM, 1 winger and 1 striker with something like 150 mill EUR. To build a world class team they need world class players and sadly these will cost a fortune. Pogba would likely take 2 thirds of their budget alone and so they should not even try to sign his ilk. They should rather try to go for pjanic and the likes who would cost them about 50 mill (remember this is Mancity buying) and would not lift City to the level of Bayern. Neymar, Suarez, Bale and the likes are equally out of the question.
So what other good wingers are there? Anderson? 50 mill and is still not good enough to compete with the best. Mahrez? maybe but again we dont know how good he is. I cant even think of good wingers to get that are purchasable. Similarly, they will have to try really hard to get a good striker as well for 50 mill today.
In general, my points are
(1) City will have to spend a lot.
(2) Despite spending a lot, they cannot make marquee signings if they want Pep to have a complete squad.
(3) If City were to build a complete squad and not waste all the budget on one star player, then their squad will be composed of largely promising overpaid transfers that will most likely leave City with weaker squads than Bayern, Madrid and Obviously barca.
Taken together, Pep has a good challenge ahead of him and now he finally has a serious test. I think success will require him to change his ultra passing gameplan and if he does that well I will bow to him.