That would be a 30 second fight resulting in Floyd leaving on a stretcher with brain damage.
Boxing isn't fighting, it's boxing. Connor did an amazing job at the art of boxing against the most successful boxer that has ever lived. But no way could Floyd ever step in an octagon and expect to live. Look how bad CM Punk got mauled after training for a few years against some random MMA fighter that nobody has ever heard of.
Today, the only way someone is going to survive a round with Connor or any other high level MMA figher is someone who's a combination of olympic level wrestler, black belt in BJJ, black belt in kickboxing, or one of the new breed who's train their whole lives in the new sport of just "MMA".
Boxing will help you in a street fight. You'll know how to move and throw punches but it won't do dick diddly in a professional fight. You'll get chocked unconscious in 30 seconds or have your head kicked off.