IF they have not developed by the time they are veterans in AAA, the chance of them developing period, is the same as hitting 0 or 00 on a Roulette table.
It happens, but is rare, and not worth ruining a team to gamble.
Since computer generated stats are so important to some baseball followers, here is a computer generated view of the young boys:
AI Overview
The failure rate for top 100 baseball prospects is
about 30%, as roughly 70% make it to the major leagues. However, this varies significantly by position, with hitters having a higher success rate than pitchers. The definition of "failure" can also vary, with some analyses considering prospects who don't become All-Stars as failures, while others consider any player who doesn't make the majors a failure
I would rather have a team with Farmer, Urshela and France, than one with Miranda, Gordon and Julien.