Not if he wants to retain his belt. If he drops the belt then i am okay with him fighting whoever he wants. Whilst he is a champion he should be fighting the best.
That's the point, the belt doesn't define him. Whether or drops or keeps the belt, it's not going to change much in terms of his status in the sport.
Cotto should retire. He's a coward nowadays and boxing doesn't need that. He used to be a warrior but no more.
That Khan fight is too dangerous for Cotto. Khan is way too fast for "old lead foot". Khan will be ducked for K9.atsch