Exactly. Grealish can play as wide forward, number 10 and 8.
And Sterling can sometimes run fast.
You might argue that Grealish is better or more flexible I think your assuming it’s to clear cut in Grealish favor and assuming Sterlings current form is permanent but in any event Grealish is not a winger like Sterling or a striker like Sterling has played so I is not a replacement so you might argue we would still have to replace Sterling and we cannot fit Grealish plus a Sterling replacement and all the more important player such as left back striker and CDM