The main thing that's happened to them is Findlay Prep. A ton of guys who would have considered Oak Hill are now ending up at Findlay. There's also the charter-school thing, as some of those schools are focusing on assembling high-level talent from their areas, so guys don't have to move away from home to play with and against great competition.
If you look at the top 25 guys for the 2016 class, to the best of my knowledge only 12 of the ESPN top 25 go to what I would call "normal" high schools, either local public schools, or local, traditional, mainly catholic private schools. The rest go to places called "prep", or "academy", or just "school" (not high school).