Are you being facetious? I am aware there are around 8 billion people in the world. The market for dedicated gaming devices is a tiny fraction of that. Those 81 million new people per year are irrelevant to the discussion.
The sales limit, based on the past, is Mario Kart Wii sales of about 37m. That is the highest number of sales for a single platform game that wasn't packed in at launch (like Wii Sports). Animal Crossing is going to blow past that. It's going to set the new standard for maximum sales. What is that new record going to be? Who the hell knows?
Yeh man, was just a play on "I just feel like these numbers have to run out eventually." I'll do the little ':P' next time. :P