Will Forum RealID be applied retrospectively?

Looking for some assurance from Blizzard that the upcoming RealID change to the forums will not be applied retrospectively to historic posts.

I would have posted in the main thread but it looks a touch busy and I am worried this important question will be lost.

I, like many others, will make the choice to keep my name private and not post when the forum changes take effect. However, if this change will be made to historic posts then the choice is taken out of my hands, which is not acceptable.