The AP will totally restart. It'll be starting fresh. Shouldn't be hard for lower ranked users, higher ranks will need to work for a while to get their former ranks.
Well, the reason i suggest that there will be a swap in leaderboard names is because most of us do like to forum post, so there will be those with AP for in game achievements and those with Reputation for forum posting.
I certainly hope not. Not like it would matter, since the final say is up to the admins, and most of us have already by hook or by crook, grown used to the idea that our points will be wiped.
Why does it even matter? If the armatar system stays, I'll be sad that I'd have to regain all my AP until I get to the tiger, but that's really the only downside.