That is an interesting idea. Maybe you should treat high school sports like they do club sports in Europe. Pick a number, say 6 is that magic number, top 6 in each class move up one class bottom 6 move down.
The same issue would happen as it does in Europe. The same teams win, get bumped up, lose, get bumped down. The only reason it sticks in Europe is because teams get increased funding for playing in the higher tier. I don't think the 3A schools are gonna be happy to win a state championship, get bumped up to 4A and then get their *** handed to them.