OH just rejected it, so it may be a while. But...
Pot legalization would be a boon for many things. Tax collections would be one. Medical de-tox centers another. Even lawyers who defend people when they get into a traffic accident. Prisons would have more space for the real criminals.
I can see ice cream type trucks selling whatever drugs were legal. Just drive around and ring the bell in neighborhoods where drug use is prevalent today. Of course under-age kids would also get the drugs, as they do today, but it would just be much more acceptable. Companies that franchise these operations would have great potential.
It would also open the possibility to have other drugs and victim-less crimes to be made legal or decriminalized. Other drugs such as Meth, heroin, cocaine and would have the same arguments to become legal as Pot. Truck drivers could snort a line of coke to keep them from falling asleep on the road. A quick line after lunch would make the afternoon meetings a bit less drowzy.
Gambling and Prostitution (above the age of consent), which are also victim-less crimes would be next. Off course, they would be taxed. You can pass out condoms in high-school, but somehow its illegal for a person to charge to use them? You can offer money to someone to clean your house or mow your lawn, but offering them money for sex is somehow wrong? You can pay for dinner, rent, or a car and get sex, but if you skip the gifts and just offer the same money, it's illegal? Another great opportunity for some company.
If the Pot legal age was 18, the alcohol age would also follow suit soon, and would be a great boon to our country. Why not let marginal people have the chance to self-destruct? It would allow the self-achievers to move faster to the top.
It would be a great world if we could just keep the feral people on some sort of drug, it would lead to less problem for the rest of us.