Well, we won't kill them. We will just emasculate the masses with love and kindness and talks of feelings and understanding and collectivism and equality until their wankers shrivel off and then slowly, they fade from existence..
But maybe, we'll get lucky and end up on a genderless planet. Wouldn't that be nice? Or maybe these new Angelic Alien Beings known as Svuczulu3% will have so many genders they will all cancel one another out and we can bob for apples in the blue eternity. Much better than getting old, eh? Why worry about getting old, now?