I do think an exceptional striker would make a difference but requires them to be at Sergio's level at the very least. The biggest problem, if you will, with Kun was that he had too many injuries. If Aguero had the fitness of say Messi, his contribution would have been far higher than it was but it was damn good.
The bottom line is we have to buy a striker who is going to make better contribution as our central striker than, for example, playing Phil Foden as a "false" nine. That is an increasingly tall order.