If we take their kids (many times more than the 800K estimate), they will eventually reach a legal point where they can sponsor their illegal parents, brothers and sisters (chain migration). Within not too many years, 800K turns into many millions.
Anyone that believes that there are just 800,000 of these poor little abused children has a frigging screw loose. Just like the ones that believe there are only 12 million illegals here. It is 5 or 10 times that.