I hope the Mother's not dead either. That's one of the fan theories I really despise. I suppose in some way it could make for good tv, but you're right. The kids tone in that first season (when they were still able to film them, lol) was definitely not that of hearing a story about their deceased Mother.
Yeah, I'm hoping this was the writers playing with that theory and giving us a red herring otherwise I thought it was telegraphed too much what with making it to an old married couple, knowing each other's stories etc.