Hard Candy is by far her worst album. There would be no point in remastering it. Don't get me wrong, to each their own, but it's just not my cup of tea. It's got some good stuff on it: Give It 2 Me, Miles Away, She's Not Me, Devil Wouldn't Recognize You, but leave the Urban-Pop sound to the its feeble-minded master: Kanye.
So, in a word, no, Hard Candy shouldn't be remastered. She's got a whole collection of albums so much more deserving.