If Grealish and Harry Kane are both transferred to Manchester City, Manchester City will have sufficiently strengthened their squad. They managed to keep the squad from last year mainly.
They will seem to have paid a very high transfer fee for these two transfers (about £230M) and I think they will give a lot in return with the trophies they will win.
Man City does need a striker, at least to replace the position left by Aguero. Harry Kane is indeed a good striker, and he is shining right now. But are Man City willing to spend £160 Million just for a Harry Kane?
With £160 Million, Man City should be able to get a striker and 1 or 2 more players. But if Man City are really attracted to Harry Kane then the transfer with fantastic value will really happen.