I can foresee many coaches starting to train their favorite proteges to be left handed players. Nadal has proven that lefties can be nurtured. You can see that even now Nadal is not too comfortable with serving lefthanded. I can see the future GOAT serving lefthanded and righthanded at random and using two forehands. He will humiliate his opponents by using his righthand at the first 2 sets winning closely and then begals his opponent by switching to his lefthand.