As a middle name, I don't think it's dated. It goes well with a lot of first names and has been popular as a middle name for a good long while. Though it is more dated as a first name I think it's still attractive and not outstanding in its datedness.
I know one Michelle who is called Mickey, but all the other Michelles I've known have just been Michelle, and the two Shelleys I have known weren't nns for anything. (There was a girl in high school with me named Shelliette, but she never went by Shelley.)
I think, therefore I judge.