It's up to Hatton, if he wants a succesful future, it's at 140, if he wants a very risky crack at glory, it's at 147.

He doesn't have very long left either way IMO, maybe a couple of years due to his style at the very top. But I agree, it's probably the prospect of the lighter fighters coming up the most likely way for another huge fight, and as you said, he needs the prospect of huge fight on the horizon as motivation to get up for the likes of Malignaggi/Witter which are loseable fights themselves even with a lot of hunger still left.