First of all, even if people in high places (why yes, I am that good) start thinking legalization of <your-favorite-chemical-here> might be a good idea, it'll take years, decades even, to come up with a sound policy about exactly how to do it, what degree of legality is involved, and how to enforce it.
After that happens, do you really think many peoples' lives will be changed? You can't even smoke cigarettes in bars anymore; do you think you'll be able to smoke pot on the street? Probably not. Will you see high/spun/tripping people everywhere? No. You'll go about your business as usual, and if you're the sort of person that wants to do these drugs, you'll still be doing them in the same places, under the same circumstances, as before. Maybe 50 years later culture will get around to adjusting to it, but I can't see it. Maybe I'm too young, or too old, or just too cynical.