Traditionally, you'd expect December to be flat or up by as much as three fold on November, so it will definitely be something if PS4 / X1 decline from November.
There is a part of me that still thinks there is something of a COD / Comic Book movie type launch to the Xbox 1 and PS4 launches - everyone who wants the product rushes out. The question is really just the decay - I don't think the lineups / prices / competition support another 2m month for X1 and PS4 - you can buy a PS3 / X360 with a selection of over 1,000 games at a cheaper price than PS4 / X1. We're probably looking at 1.5m to 2.0m in total for Nov-Dec for both PS4 / X1 - with November simply getting the bulk of the share instead of December as it usually is.
Long term, we'll probably see PS4 ramp up to 10-15m in 2014, with X1 doing more like 7-11m for the year.
People are difficult to govern because they have too much knowledge.
When there are more laws, there are more criminals.
- Lao Tzu
