If it does somehow get legalized, businesses will have to be careful in regulation of their employees, considering the effects of weed tend to stay around for a while, and is somewhat similar to alcohol in it's effects. Also, weed should be prohibited from any place that bans alcohol or tobacco smoking.
Again I think it all comes down to how much you get high, if you get high 6 out of 7 days of a week (Nonstop) of course you're going to feel bad afterward.
Still, a good amount of people in the population will depend on it, and develop a psychological addiction to it, if not physical.