He would be, we've been through this already.
He was here for 30 months, he's 100% moving this summer when he'd be 20, so he'd have been registered with us for over 40 months by the time the cutoff is, and he only needs 36.
- A "club-trained player" is a player who, between the age of 15 (or the start of the season during which he turns 15) and 21 (or the end of the season during which he turns 21), and irrespective of his nationality and age, has been registered with his current club for a period, continuous or not, of three entire seasons (i.e. a period starting with the first official match of the relevant national championship and ending with the last official match of that relevant national championship) or of 36 months.
I would say that with Sterling talking about going to Spain at some point, Sancho becomes an absolute must-buy if Sané decides to go. There's very few world class homegrown players, and getting a club trained one, not just HG would be invaluable.
Think how much we'd actually pay to change Sané's registration to club trained and get another foreign player spot opened up if it was an option.