Well there's unlikely to be a 4.5M or more difference in sold numbers in 2011 in favour of the PS3 especially given the fact that the Xbox 360 enters into 2011 in a stronger sales position. Beyond this any large price cut will either be matched or even pre-empted by Microsoft given the fact that from an operational perspective their Xbox 360 business is much more profitable and they have both higher gross margins per Xbox 360 sold and their higher operational margins are coming from things like online revenue etc and overall software revenues combined won't likely diminish over the coming 12 months.
By the time any PS3 price cut is made the difference may be as high as 5-6M units if you count Q1/Q2 and Q3 sales up until that point. From the point of that expected price cut with the difference in units sold it would probably take at least 12 months even with a severe $100 price cut for the difference to be overturned. That takes us all the way up to late 2012 if not later. Then once a new generation starts, the Xbox 360 will be 7 in 2012 so betting against a new generation starts becoming a poor bet to make after that point, then all bets are off and all userbases are up for grabs, PS3 inclusive.
Tease.







