"I don't know if he will come back into the English game, I'm not sure of that," Ferguson told the League Managers Association website.
"I think Jose will end up at a top team in Spain or Italy, I'm almost certain of that.
"There certainly is no-one on the radar at the moment obviously, he's taking a break and I think he's aiming to come back fresh.
"I don't think there's any problem about him coming back into management, I think it's where he comes back in and I don't think anyone has any clues to that at this moment in time."
Ferguson warned that managers cannot be out of the game too long because they will become forgotten - although he conceded that will not happen to Mourinho.
"He's been around quite a few clubs, Brian, but he's been out of the game for about three years now and you get forgotten about.
"It is ridiculous, but being out of the game that long is a handicap because with his qualities and his CV, Brian Little could quite easily manage 80% of the clubs in England."