I believe MGS5 will be on the X360/Xbox 3 for sure. So many other franchises have gone-multiplatform and sort of paved the way, that it's not longer taboo to release on the X360. In the coming years most companies, incl Konami, will want to maximise profits.
GT6, no. Not only because Sony owns it, but because the X360 already has Forza.
FF14, no. Spinoffs yes, but core game no. This I believe for two reasons. One is that FF is a franchise in decline, and I think FF13 will prove that. The other is that I don't think the Xbox demographics care so much for JPRPGs as Sony-fans do. I NEVER hear X360-fans say they wish we would get FF. I never hear any hints of envy towards the PS3 owners who will get FF13. I think the sales of FF-spinoffs on the X360 will be bad.
So overall, the need for Sony to keep FF core game exlusive is stronger than the attraction from selling a couple of mill on the X360.