I'll keep it in mind. I haven't yet decided what to do when we run out of people to do an AMA, but just redoing some people who've done one before is one of the options.
Still, new people wanting to answer question is going to be the priority
One thing that I think might help would be to somehow 'pin' a current AMA to the top of the Community Posts forum list so that it doesn't get buried underneath a flurry of posts or new activity.