Khabib has too big of an ego of himself to leave the UFC before establishing himself as the undisputable best LW on the planet. He won't leave it to controversy. He will fight Tony one day,and that's what his father wants too. It's clear from his past fights he won't leave it to dispute. People bitch about him alot before, about him having shitty stand up and what did he do to counter that? He stood with Conor for an entire round just to prove a point. Also, he will be branded as a coward and a duck if he ever retire before facing Tony. He knows that. Seeing how much he value bravery and integrity, and how much he shuns being a pussy, he would never not fight Tony So no, I believe he would never retire until there's no more guys left to contest his legacy.