I honestly don't know too many details about how stuff is for people who fall through the cracks.
At least until you are 18 you usually have access to various programs designed to help you. After that it gets tougher and usually you have to deal with social services. They help, but it's not a fun situation.
I know its just anecdotal, but my brother was a victim of the shitty school system in Kentucky and despite being an intelligent guy he floated through high school not applying himself and realized too late what that meant for his future. He is one of the lucky ones as he at least has a stable retail job even if its basically a dead end. He hates it and regrets not applying himself in high school but now he has car payments and rent and such so he's kinda stuck where he is.
Most of his HS friends who also slipped through the cracks are currently in rehab or dead from meth addiction. So yeah, I'm glad he at least landed on his feet even if he's not really happy.
Honestly, the only difference between us is the fact that my mother was fairly strict and from a young age instilled good study habits and such into me, as she was a high school drop out herself and didn't want that for me. On the other hand, my brother lived with his dad (I'll just mention we are technically half brothers just so things don't get confusing) and he kind of spoiled my brother and let him underachieve.
So yeah, even if I don't trust an underfunded district to pull this off I honestly don't have that big of a problem with this idea as a concept.
Problem is that this is America and I expect most school districts to just say fuck it and basically funnel most struggling students into
the armed services which is the last goddamn thing the country needs.