I hope you're correct on the bolded, but I'm not sure you are/will be. Here's why I'm not so sure:
Society today is more polarized than ever before. There are far more people with extreme ideological views, both on the right and left, than ever before. This is evidence by the rise and popularity of Donald Trump, Ted Cruz, and Bernie Sanders, some of the most ideologically extreme major-party presidential candidates in our country's history (in Trump's case I don't think his actual positions are as extreme as some believe they are, but the rhetoric he uses to promote them certainly is). That said, when these kids move into the "real world" will their "dumb, idealistic, impulsive ideas" actually fade away? At this point, I'm not so sure. We've already gotten to the point where what I would consider to be idealistic, fantasy-land ideas like free college tuition and a federally-mandated $15 minimum wage are being embraced by a large portion of the populace and where college administrators are being forced into resignation for suggesting that maybe it's not appropriate or necessary for the administration of a world-class university home to the best and brightest students on the planet to lay out explicit guidelines around appropriate Halloween costumes. It seems to me that these ideas are moving out into the real world and taken seriously.
The Hippies of the 1960s and 1970s made people take notice, too. But, they melted into American culture, like their Greaser parents before them. The Hippy movement also began on college campuses as an anti-war movement, but got more outrageous and almost silly as time went on. By the late 60s, they were almost cartoons of themselves. And as they grew up, their "movement" faded as the young idealistic practitioners of their philosophy assimilated into the real world, got jobs, secured mortgages, raised kids, and became the square, out of touch parents of their own children, rebelling in their own unique subcultures.
It's the circle of American culture. Some of the craziness will linger for some time but it will taper off. On the other hand, some of the good stuff worth holding onto might survive (less racism, for one) and the country will be better for it -- even if we cannot see how all this silliness can produce anything positive. Eventually they will mostly come to grips with the reality that their parents were right about a whole lot more than they were wrong about -- just like you and I did, and our parents before us, and theirs before them.
Like these kids today, the heart of the Hippies was always in the right place. They wanted to bring about a better world and they gave it their best shot in their own way. They hung on to what worked and tossed off what didn't. These "crazy" kids today will do the same.
I run into a Hippy or two from back in the day, and they always make me smile. They are the ones who didn't want to give up the cause and they, by and large, exist somewhere on the fringes of society, or have embraced some workable form of duality that lets them make a living, but still hang on to the old ideology. I suspect there will be some hold-outs in this current generation, too, freaking out over chalk drawings on the sidewalk, or demanding that we pretend men are women or vice versa. But, they will move out toward the edges of society just as the hangers-on of every generation have before them.
I suspect that these rebellious, "destructive" behaviors of youth always look worse in the moments they are new. But, this too shall pass.