We know what would happen because we have a model: Europe. In Europe colleges offer the bare minimum by way of amenities (since the state often pays for a large chunk of the tuition, the state insists on the colleges being streamlined for costs). European universities have sports teams, but they are general intramural level competition and done just for fun (not tied into the academic system or admissions). In Europe, there are general 3 levels of soccer play: the academies which are ruthless in their tracking (and once you are off the academic track, its very difficult to get back on) and develop professional soccer players; a small pay to play system which consists largely of players either cut off the academy track (and trying to get back on) or players trying to make their way onto the academy track; and everyone else plays rec (which, unlike the old AYSO, is tiered in multiple levels).
So yes, if college soccer did not exist, it is likely soccer clubs would exist but like in Europe, the entire operation would be smaller (similar to what we had in the 1970s when only the really exceptional kids would play club soccer). The problem with "maximize their childs potential" is that once there is a distortion in the system, it impacts everyone, whether they are aiming for college admissions or merely to "maximize their child's potential". Because once some people take off on intensive specialization, to "maximize potential" you'll have to play the game to keep up, even if the end goal isn't college (which in the end as they get older for a ton of kids turns out just not to be worth it, leading to the drop off in numbers the closer you get to senior year of high school).