Yeah, that's true, and there's also a possible negative feedback loop if strongly religious colleges that weren't as interested in secular education made a revival. Super-Christian private high schools feeding into super-Christian colleges won't have the same sort of check on whether the student got any sort of decent secular education, because right now, the need to look good to a college with a mostly secular admissions process (even schools like BYU look at secular academics in the admissions) is one of the main motivators for religious high schools to do a decent job on their secular education.