So of the 26 players that Bruce Arena called in for the upcoming WCQs, 15 played college soccer, including 7 who played four years of college ball. That's the good news for college soccer. The bad is that of those 7, all but one (Matt Hedges, who is 27) were born in the 80s and are already in or will be in their 30s in the next couple of months. It reinforces the theory that there are fewer and fewer younger players in the USMNT pool who played 4 years of college soccer.
In addition to Martin, Lade, and Ford, a few other guys played college soccer: Nathan Smith, Kevin Ellis (JuCo), and Evan Louro
Interesting podcast from the UK featuring former DeMatha High School (Maryland) and former DC United U20 and U23 coach Daffydd Evans discussing some issues relative to pairing soccer and academics both in the US and in the UK, including some brief remarks on college and college soccer players in the US. http://mindsetgame.libsyn.com/39-dafydd-evans-academy-vs-us-collegiate-system-in-football-soccer
Yours is not a very controversial theory. It is pretty obvious that few elite players are going to play 4 years of college sports and an increasing amount of soccer players are going to play none. I believe Stanford is one of the most selective (i'm not sure how they rate against Cal Tech which isn't know for professional athletic alums) and even they have kids like Morris and Kovar that turn pro early. UCLA which is a very good school had half their starters leave early last year. I heard a story of a local kid who's mom was a principle of a school. She made him promise he'd get his degree. But when the NBA offered millions to come how early she told him to take the money as no normal job was gong to pay like that. As MLS starts pay competitive salaries to US kids, more are going to leave early. But just like baseball, some are going to spend time in college before going pro.
Through a North American sports lens hockey is atypical in that there is a non-university amateur route past high school. But at the University where I work, we have a bunch of European kids coming in as 20+ y/o freshmen in track and field, basketball, hockey, and swimming. The biggest NCAA eligibility issues we run into are tied to academics, not amateur status. I imagine the NCAA's rules are amateurism are confusing and annoyingly complex, but I'd hope it boils down to whether you got a paycheck...