More than likely we will have gheettos all over the world, It will be full of shit. Children with guns will go around fighting and killing eac h other.
The few intelligent and good kids will be bruttally murdered and territorial wars will flare. Upto age 20 there will be no doctors so death rate will increase. Also I am pretty sure all the wild animals will have a feast.
Most likely we will see them extinct or living in caves.