Despite the evidence that supports the fact that there does exist a link between childhood attachment and eventual social well-being, I believe that there are still several other factors that can contribute to the future of the children raised. As mentioned in another post, the environment in which the child is raised can contribute immensely to what the child will think of the world in the future.
There are also cases where this attachment can be made to be very secure, but because of troubling events that may occur in the child's adolescence, that attachment can break off, and it may not come back again; therefore, events in the child's life (with his/her parents or even with his/her peers) do have the capacity to change the social well-being of a child.
I like that you also included changes that might occur after young childhood because you are right. There are definitely events that might happen to interrupt or change the secure attachment the person felt as a child. I agree completely that a child's surroundings play a huge role in attachment and later happiness in life.
I agree. I also believe that even though studies show a pretty clear correlation between healthy childhood attachment and later well-being, there are way too many factors to flat-out claim that if a child develops a attachment, he/she must therefore have a well-balanced and healthy social and personal life in the future, through adolescence and adulthood. But regardless, I do believe that if nothing major or seriously bad happens to the child during childhood or adolescence, the child should theoretically grow up to be healthy mentally and well balanced.