That's something of an overstatement. Marijuana is only legal in a few states now, most states still keeping it illegal. It's just that people are beginning to turn against it. I don't get the impression that it's generational at all, only that over forty years of fighting against drugs has not led to the kind of results we were promised. Still very much in the minority, as even legalizing pot is controversial, but it is beginning to grow.
I expect after the war, we'll stop enforcing drug laws because we'll have far bigger worries on our mind.