During this period last year, the X360 sold 8.5-9M (I'm not sure how much, VGChartz is messing up for me).
If we assume a 33% drop, That would leave it at 5.5-6M. This would require for the Ps3 to sell 13.5-14M. That won't be the highest ever - that was my mistake.
The Wii sold 16.5M in that period last year. The DS has also exceeded it.
However, it seems to be roughly as much as the Ps2 did at its peak. In other news, your bet will require that
1. The X360 drops almost as much as possible
2. The Ps3 matches the peak of the Ps2. At this time, the Ps2 had dropped to 149 dollars (I believe), and there was no economic crisis. Additionally, it had far larger sales in Japan than the Ps3 will. In other news, it will have to outperform the Ps2's best in Europe and Americas.
