Almost any name could come back in the future. I think it's a least a decade too early for
Mildred in the USA, though. Too many young parents still remember elderly Mildreds, and a lot of people seem to really dislike the final syllable, associating it with the word "dread".
Personally I wish that Milbrey, the name of the original medieval St.
Mildred's sister, would come back.