Hatton has at least as good a chance of taking out the December bout as Mayweather. Possibly better than evens.
IMO, irrespective of how fit Mayweather is, fighting on the backfoot with your opponent on your chest for 36 minutes is tough going. If Mayweather fights Hatton in the same fashion as he has done every other opponent for the past five years, he will lose early rounds due to Hatton's superior activity and be drained - which takes away his precision and power- for the later rounds.
For Mayweather to win, he must be far more active, which brings Hatton even further into the fight. Hatton's footspeed will ensure that he is always on top of Floyd and if Floyd opens up, he will get outdone on the inside. Hatton is simply better at it. Though Hatton may get caught on coming in several times, he has proven he can work through a good shot. Hatton is an incredibly good chance in this fight.
What befuddles me somewhat though, is how many of you Poms 'pay homage' to Mayweather's 'greatness' on the infantile general forums. I constantly read such statements as, 'I expect Floyd to win, but Hatton to make a good account of himself.' Whilst you at least you never sound like braggarts, Poms always tend to overrate their opponents. IMO it is why you are often not as successful as sport as you should be. Mayweather is incredibly good, but hardly on another level to Hatton. Have a little more faith in your man!