Well X360 boosted it's sales this christmas and pre-christmas period due to excelent line-up, free LIVE in some bundles and a price cut. PS3 was outselling it all year since that happenend.
So From now on, the PS3 will for shure have a price cut and I bet that Killzone2 will boost it like MGS4 did. The question, with a gap now counting 8 Million from Microsoft machine, will it be on time to overtake 360 and gain the second place?
I personally think not, it would end up the generation really close, but not surpass.