They will be dominant as long Pep is there despite the money probably. Yes, they can dwarf anyone with money power, but there are so many examples of money thrown without so much influence. For example, Pep with his style of play can field this front 6 without any problem.
Foden ---- number 9 ---- Mahrez
Grealish --- De Bruyne
Rodri
And it will work because of their playing style to devastating effect. Hypothetically, of course, but you get the point. No other coach can field that midfield without being unbalanced because he will not have that advantage in possession. Grealish is also a worry because he can rotate with Foden and even play false 9 if required. This is a transfer that should be prevented, but only in the context of Pep tactics.
What we should do no matter if City looking unstoppable is get our shit together and be the first in line to take over. No top 4 bollocks anymore, announce serious intent with transfers and start hitting 80+ points in the league regularly. Or in other words, start overachieving with our squad, we have done that regularly before.