From this highly-touted group, I'd say four regulars, who if they hang in there long enough should have two All-Stars (that it, two selected to an AS team, but without MVP votes or HOF WAR).
The odds are so against an actual group making the majors together in two or three-year spans, and then all becoming immediate All-Stars or even Rookie of the Years...
... like the Braves: Acuna, Albies, Riley, Harris etc.
Plus, though the Sox have a history of homegrown stars, there are plenty of overrated prospects who also fizzle out, once they arrive in the MLB (and leagues develop "books" on them).
Guys that are really young have plenty of time to develop talents, but that's also extra time to pick up bad habits, unhealthy lifestyles, and subsequent injuries that may hamper progress.
To that end, there's something to be said for drafting solid college stars like Matt McLain -- he may have a lower ceiling than 5-tool teenagers, but there's a higher floor to count on...