Assuming you keeps the forums in their current scope (*cough*), are you going to keep our posts or not? If you don't, how will our forum post AP count work? As an example, if you were to erase all the forum posts, I would drop to just below 1000AP of my current 3700 or so. While not all that important, that would put a dent in my e-go, so yeah.
As to the original question, I'm looking for a way to migrate the forum posts to some new engine. It's too early to tell yet, and we also don't have any plans to keep an online archive of the old forums once we launch AG3.
We'll be keeping track of everyone's AP *before* they moved to AG3. Even if we reset/wipe/discontinue the forums, we'll still know how many AP you had on AG2 and grant points/karma/achievements based on that value.