There was a recent black on black murder where it happened over a $5 dice game..right outside a funeral the people had just been attending.
In other words: they will find a reason to slaughter each other. If not drugs it will just be something else.
It's also not just about making drugs legal, that won't get rid of drug dealers. If you go to somewhere like Denver right now and you buy weed legally you will notice it's expensive as f*ck. It does not reflect the prices you would pay on the streets which could be substantially less. Thus the drug dealers would still have a place among the poor.
So we need it all legalized and then it should actually be made so it's cheaper to buy it legally than it is to get it on the street. After all they could charge tax, etc. on these purchases and more than make their money back.