Why did Square Enix stick with Sony?

[ps3_jrpg_gamer]

JayLam said:
Final Fantasy XIV will on X360 sooner or later，don't forget FF XIII was only on PS3 at begining.If FF XIII Versus’s producer isn't Tetsuya Nomura，maybe it will on X360 too.
So Square Enix stick with SONY？

check the E3 2006 TRAILER it says for play station3 not "only for play station 3"

then the developers where thinking of bringing the series to 360 and since then rumours for a 360 version were floating around until E3 2008

but if you check versus 13 DKS37 trailer it says Only for Play Station 3 WORLDWIDE