Contracts for minors are binding in honour only. (They have no legal standing whatsoever).
If a player is good enough, clubs will continue to want him on their books well after any prior (informal) commitment has lapsed. I used to teach a youngster who was probably the best all round sportsman I've ever come across but, throughout his schooldays, he only wanted to play sport for fun. He refused the offer of subsidised tennis coaching (which was offered because he had the most outstanding talent that the school's head of PE had ever seen). He wasn't interested in seeking a career in professional cricket (despite being able to bowl at nearly 90mph at the age of 13, with devastating accuracy and the ability to turn the ball both ways). He also rejected all approaches from professional football clubs (despite me urging him to seek trials, because he was incredibly talented). Yet, several years after leaving school, he came back to tell me that he'd finally taken my advice and had been for a professional trial. On the basis of that one trial, he'd decided to quit his job (at a time of high unemployment) and join Chesterfield FC. They played him in their youth team for just one match and then (without even passing through the reserves) he had a regular full first team place.
The point of my story is to show that really good players will always be able to get into professional football, irrespective of 'coaching schemes', 'contracts', 'scholarships' or whatever. (Regrettably, Bob Bloomer later had to quit football through injury. Otherwise he would almost certainly have been playing at international level within a few years).
Chris