I don't see him coming back, although as has been said he does have a history of changing his mind. There is nothing big enough for him now, and it would be too late by the time there was.
I think he timed his retirement just right - his skills were not as sharp in his last 2 fights, he was down in the last 2 and against Salem not long before that, and his power seemed to recede with each fight. Not saying he was finished, far from it, but he was only going one way.

Although having said that this has been the longest period his hands have had pain free in 20 years. If he did come back i picture a spectacular and unexpected knockout! (for him )