I feel bad for exceptionally gifted children. There is so much pressure on them to do something spectacular in adulthood, like becoming the next Bill Gates.
I don't see anything wrong with beginning college at 16 if the child is mature.
Our son's giftedness is in math and music. It was astonishing to us when he hummed tunes of whole songs when he was 8 months old in perfect pitch. He taught himself to read at 2 and was reciting math tables to us at 2 1/2 years. When at 3, he began a discussion with me one day about the skeletal structure of the human hand, I got down on my knees.
My husband and I prayed a great deal that God would lead us what to do with this child. So, we are here at home working on his whole character. And he is perfectly happy conjugating his Latin verbs, learning his theorems, composing his pieces on the piano and challenging himself on difficult violin pieces.
On top of that, he is earning his Scout merit badges, acolyting at church, and learning to be a cantor.
He just became a teenager, and so far, praise be to God, he is blessedly free of that youthful angst so prevalent in today's teens. Plus, we have other children and it would not have been right to have focused all our energy on just one child's pursuit of excellence.
By the time he's 16, he will probably be at the local university taking calculus and music theory classes. In the meantime, we try to enjoy him and his siblings because they truly are a joy to us.