Foden would play on the left (Sane's position), Grealish in place of Silva.
I don't see it personally, I've not seen evidence he has anything like the same touch, passing range or vision as Silva. Seems like a bit of a prima donna off the pitch too. A classic United signing in recent years, although they seem to have sorted that out under Solskjaer now.
We get linked with these sorts of players every season, probably stories planted by agents or clubs to drive up prices.