I think the business model relies on only one or two breaking into the first team each season. Some of these will stay and become valued team members (JWP) or be sold for decent money (Chambers, Targett, Reed for example). I think there are a few names to watch out for at U18 level including Mitchell and Rodriguez but very early days - these guys are very young. You won't see 17 year olds breaking through to the first team in the same way as Walcott and the Ox did when we were in the lower leagues. That said, I can't help feeling that their development is a bit behind schedule. Watching the cup game the other night they were by far the better team but seemed too often to need about three touches to get the ball under control. You're lucky if you get one in the EPL!
They discussed this on the Total Saints Podcast a couple of weeks ago. It was agreed that the Playbook, which has only been in operation for less than a year across the age groups, will take a few years to show any results, so even the rising stars are artificially being held back at the moment.
Interesting 'trialist' at No 9 who was replaced in the first minute - or is that a typo....? Edit: possibly great great grandson of George Weah?
https://www.southamptonfc.com/u18s/matches/2020-21/saints-vs-arsenal-2021-04-06 U18's draw 2 - 2 with Arsenal Pearce with both including a penalty.