I don't know if it means anything or that she's definitely returning to voice Suigintou in the new Rozen Maiden TV anime, but last week Tanaka Rie made a few tweets regarding her Suigintou doll which she received several years ago and her new chair, including links to a couple of pics of the doll
here and
here sitting in the chair.
Why would Tanaka Rie buy Suigintou a new chair and show it off if she isn't coming back to do Suigintou's voice?