My son went to school until Spring Break of his 8th grade year. At that point, I had had it with him not knowing how to write, and not even knowing his basic math facts. I told him that we had four years to get him ready for college and that it would take all four.My sister has done the same thing with one of her daughters. They did a California variant of homeschooling for 8th grade,* then public high school for 9th. Most of the subjects in 9th grade were so low level that she enrolled in community college for 10th. It's worked out well.
I was a little concerned about him getting into college from a homeschooling situation, but he applied to 6 schools and was accepted at all 6. He was strong enough academically to take Chemistry at the community college his junior year, and Writing and Physics there his senior year. The school I removed him from felt good if their students were ready for the community college after high school. I used the community college as part of high school to get him ready for university. What a difference in expectations!
One of the things that really stands out for me: When my son came home from taking his first PSAT test, the first thing he said was, "Thank you for making me learn my math facts. The first math problem was a simple doubling problem and I had it answered by the time everyone else got their calculators out."
* It's not homeschooling....consultant schooling, maybe? I believe this option was created for students who are acting or perhaps homebound. There is a consulting teacher & texts are provided by the state. On the other hand, the parent can choose which textbooks his child uses. It's similar to what we would call Independent Study.