Norris Cole's stock is quickly rising. Joell could never be better than just a filler portion of a trade. Essentially Cole for another piece. Doubt the Kings will do it considering their backcourt is already jammed and he wouldn't improve the chemistry there.
Miami's not going to trade Joel Anthony unless they can take a better big man in the trade. that would leave their center rotation very thin. Joel also gives them the option to defend the pick n roll better if they're having trouble with it.