How does one know if a student will succeed in college? Past performance is no guarantee for future success or failure. I know ample examples where students were really bad academically until grade 12, and then flourished in the college/university environment and vice versa.

Until students try, they will not know. One way out of this is to give students an escape hatch so that they can easily switch from college to trade school if they so desire without impacting their academics.