If he develops into a top drawer first choice striker I don't care how old he is if he's doing the biz.
But if he hasn't developed as we hope and still knocking about as 3rd choice by the time he's 23/24, it's very unlikely he'll ever take that final step up. So I'd rather his place in the squad be taken by another up and coming youngster, either bought in or through the academy. The lad himself would probably be looking for more game time anyway by that stage.
Yeh, I’m mainly aiming it at those saying sign a first choice striker now AND sell him. Like we can’t he be back-up to develop at his age? To some we can only have one striker at the club apparently.