Hockey and baseball have well-developed minor league systems. And, still, I'd question whether those sports "do fine" except at the very top levels. What about the kid who gets drafted out of HS, goes pro and washes out? You know . . . like the vast, vast majority of pro ballplayers (currently, there are 40 rounds of the draft and 30 teams; that's up to 1,200 drafted every year. Then there are the international players no subject to the draft. There are also 1,200 on the 30 teams' "40 man rosters" (25 from the active roster + 15 minor league players). MOST do not make the top level (most don't even make AAA).
@Mullet also mentioned golf and tennis. Again, at the top levels - the players that casual observers like me hear about - they may make a great living. And, in a sense, if people are watching, the sports "do fine". But do the athletes? I'd question that all the pros in golf and tennis who had the opportunity to play in college but went pro instead - even a fraction of those pros - would not have benefitted from a subsidized education, joining the pro ranks later and/or turning their education into something else.
We run the risk of turning anecdote - Push, Horan, Moultrie - into trends or into representatives of the whole. Soon we will have a big group of soccer NT players who did not play HS but will that really be evidence that HS is bad for soccer development? I mean, if US Soccer is focusing on DA (as it is), the resulting sample is not really indicative of anything other than a clear policy for recruitment. The current senior players - and college age players in the older YNT teams - are likely more representative because they had choice. And most chose - overwhelmingly to play HS.