When I say "high school movies," I basically mean '80s high school movies. I honestly don't think you can make a Ferris Bueller or a Sixteen Candles today "unironically" -- or what have you. (Ironic is in, on the other hand -- see Superbad, Napoleon Dynamite, 21 Jump Street, Clueless.) High school as a setting isn't going away ever, though I wish we all could at least take a sabbatical in order to come up with some original plots. Transformers was sort of set in high school, at least the first one was. And so on. But high school as a memetic (keep in mind I originally mentioned the high school trope, not the high school movie; different animals -- realistically I know it won't vanish but I don't think we'll ever see the Porky's style again per se.
Garden State was basically Ferris Beuller's Day Off done for millenials. When you say "the high school trope" you're basically talking about "coming of age romances" which are not going to go away. I would argue that Boy's Town was as much a part of "the high school trope" as Breakfast Club and it was long enough ago that Mickey Rooney played a 15-year-old. You want original plots? Go watch Brick. Report back for science.
Yeah, I've seen Brick. Falls into the movies set around high school but not "high school movies" (coming of age romances, sure) category. It seems to me that what's largely replaced the sort of movie you mention is the mid-twenties rom-com, the Adam Sandler/Jennifer Aniston/Ashton Kutcher stuff. My main problem with arguing this is that I watch good movies almost exclusively. So my data set is incomplete.