Usain Bolt is a genius. I can't think, other than Muhammad Ali, of anybody that has so had an impact inside or beyond their sport.
You can have the Friday-night-in-the-pub conversations about who is best footballer or tennis player, but there is no argument about this guy in sprinting
We are not going to replace Usain Bolt - not because you are not going to have a trophy cabinet full of three back-to-back Olympic doubles and relays and World Championships - you are just not going to replace him because his personality dominated not just our sport but pretty much every sport out there