Unreal Engine 3 is -everywhere-, that's it's main draw, I think. Heck, it's even supported by web-browsers now - so the sheer range and ease that you can reach with it makes it absolutely viable, no matter the age.
With Squeenix's proprietry stuff - like the Crystal Engine and Luminous above - the opposite is true; while they managed to port FFXIII over to Xbox well enough, I wouldn't be surprised if the engine didn't cause them a massive ball-ache, because it was initially built for PS3.
Unreal Engine 3 wouldn't have that problem.
Still, I stand by my inference that this is a sign that next-gen is still a ways away - unless this is for immediate-term stuff, and they're working on the next gen titles in the background, which may very well also be true.