My prediction:
We know for sure that PS3 was at 70m mark at the beginning of November. Last Q3 they shipped 6.5m PS3. This year I predict -15% (in line with sales in US & JP which we know are over 700k worse than last Q3) = around 5.5 for this Q3 = around 74.5m for PS3 at the end of 2012.