As the great Eddie Waring once said, apropos a head injury to a rugby league player: "It's a good job it was his head, it might have done him some damage otherwise".
A different ball game altogether with the modern light balls that ate used - nothing like the laced up leather bombs (or worse still, basketballs) that we had to head at school. Heading is much less painful than it used to be!
However, in the spirit of getting rid of head tennis (the most boring form of football that I can think of), how about banning heading outside of the penalty area unless the ball has bounced first? Still allow the flying header that scores a goal (or clears the ball) from a corner - but just heading back the GK's long kick, or the hoof out from defence, no: not allowed - let it bounce first. Can't see that that would be any harder to adapt to than the back-pass rule.