This is probably something you couldn't do in the public system, and you would need separate schools, and arguably this is what private schools already do. Policy wise, this is equivalent to vouchers, which are immensely controversial for the same reasons gifted education is, because they stream people into opportunity - or lack thereof, when they are still just kids. You're never going to teach kids enough to overthrow you, but if you don't, what are you really educating them to become?