What becomes of most of the childhood bullies? Are they the future sociopaths?

Bullies. Depends on their goal in life, social stability, mental health and their support system.
Insecurity. Some go out of bullying others as a phase they unfortunately pass through. Others continue bullying into adult life. Believe it or not, most bullies are no sociopaths. Most in fact have inferiority complexes and pick on safe targets to bolster their often profoundly damaged self esteem.