The simple solution (on paper) is to blow up the NCAA and pursue the sports academy route used most notably in Euro football. A person focuses either on academics or sport. If sport, they receive $ and can fully focus their efforts on sport. If academics, they fully focus their efforts on upper/secondary school. There is no overlap, there is no redshirt, there is only the chosen focus.
Death to the NCAA... but it may mean death to ours and many other olympic sports if it comes to fruition.