This is a good thread subject, but I agree with several of the posts above. I love RPG's and since day one the only thing I wished my X360 would have is FFXIII. With the loss of its exclusivity, less people will buy a PS3 if they already have a X360.
That being said, with FFXIII now released on the X360 gives me no reason to purchase the PS3 for its exclusives. It's just not worth $400 + the games I would like to play. Dont get me wrong, the PS3 is an excellent system. But for my tastes, its defining game WAS FFXIII. I have an HD-DVD player with about 20+ great titles, so I can wait a bit for Blu-Ray prices to drop before investing in that market. At $13 a HDDVD now that BR won the war, and with the same quality as BR, I am quickly building an HD library until I invest in a (cheaper than PS3) Blu-Ray player, hopefully during this holiday.
I dont for-see a large boost in Hardware for X360 because of FFXIII, more, a steady selling rate slightly higher than the current monthly averages. I do see a possible drop in PS3 Hardware considering people who...like me....wanted a PS3 for FFXIII, and are now, not going to be getting one. As stated, people are guessing an average of 1mil in FFXIII sales on X360. How many of that 1mil would have bought a PS3 to experience FFXIII. I WAS at least (1), but no longer. PS3 will most likely take 2nd place, but my guess now is mid to late 2010 instead of 2009 like most thought.