Not sure why you feel this will be the case. We won't offer contracts to every old player (we know for a fact a number of them are out the door) and even if we did that doesn't stop us from bringing in world class talent.
Last summer we brought in two players who would arguably be desired by every big side in Europe in Gabriel Jesus and Leroy Sane. We also got Barcelona and Chile's number 1 and England's most promising play-making central defender in an age.
Even another window on that level, and I think most here expect even more, would be amazing given the foundation laid already.
The underlying point you're making though is that ultimately we'll fail to acquire most of our transfer targets, which doesn't seem likely at all. City have the financial clout, the promise of trophies/success and of course Pep Guardiola, all of which is a serious lure for any player in the game. The Laportes are the exceptions.