Unless his mentality changes he's not going to be of much use. I am writing him off for next season personally. I know the striker areas are highly covered when it comes to addressing need but I remember watching countless games last season where if the club had some attacking intent from the wide players that would resemble even 6/10 performance levels, the team would have amassed far more points with a higher chance creation and conversion ratio. I think Antony is still raw but is presently twice the player simply down to his mindset alone.
There are too many factors that have to be in place for Sancho to be successful. Needs movement around him consistently, overlapping full back as he doesn't go outside and the tempo of the ball would have to be quick in and around the midfield because he lack athleticism. Realistically all of those conditions change simply through a different mindset (excluding the athleticism). I do hope he does come good however, a Sancho that resembled the form at Dortmund, Marcus either central or rotating and hopefully even incremental improvement from the right side with either Amad / Antony it's a good mix. But that's hypothesis not reality at this moment in time and on the premise of last season.