Segagamer is kind of right about X-Box owners not wanting Final Fantasy, the X-Box fanbase in general doesn't care too much for Final Fantasy. Here on the internet, yes, there are alot of X-Box owners that would love to see Final Fantasy, but that's only a small percent.
The reason the X-Box and the 360 are doing well here in America, but poorly everywhere else in the world is because the system is primarly an American console that's caters to a Western audience with Western games. The X-Box last gen had 38 games that sold over a million copies, yet out of those 38 only TWO were from Japanese companies. And those two games were Dead or Alive 3 from Tecmo and ESPN NFL 2K5 from Sega. Here's the rest to show the taste in games the X-Box fanbase has.
Halo 2
Halo
Tom Clancy Splinter Cell
Fable
Grand Theft Auto Double Pack
Project Gotham Racing
Need for Speed: Underground 2
Star Wars: Knights of the Republic
Grand Theft Auto: San Andreas
Elder Scrolls III: Morrowind
Tom Clancy Ghost Recon
Need for Speed: Underground
Star Wars: Battlefront
Tom Clancy Rainbow Six 3
Project Gotham Racing 2
Dead or Alive 3
Madden NFL 2005
Madden NFL 2006
Tom Clancy Splinter Cell: Pandora Tomorrow
ESPN NFL 2K5
Medal Of Honour Frontline
Star Wars: Battlefront II
Tom Clancy Ghost Recon 2
Spiderman: The Movie
True Crime: Streets of LA
Enter the Matrix
Star Wars: Knights of the Republic 2
Tony Hawks Underground
Doom III
Hitman 2: Silent Assassin
Star Wars Episode III: Revenge of the Sith
Medal Of Honour Rising Sun
Max Payne
Tom Clancy Splinter Cell: Chaos Theory
Call of Duty: Finest Hour
Need for Speed: Most Wanted
Spiderman: The Movie 2
Forza Motorsport
And here's the 360's list that shows that the taste in the X-Boxes fanbase is still the same.
Gears of War
Call of Duty 2
Tom Clancy Ghost Recon Advanced Warfighter
Madden NFL 07
Elder Scrolls IV: Oblivion
Call of Duty 3
Crackdown
Fight Night Round 3
Lost Planet: Extreme Condition (From Capcom, but very western styled)
Tom Clancy Rainbow Six: Vegas
Perfect Dark Zero
Dead Rising (Same as Lost Planet)
Saints Row
Need for Speed: Most Wanted
Need For Speed: Carbon
Once again, the X-Box is an American system that appeal primarily to Western audiences with Western games. The only Japanese games to sell well are the ones that are made to appeal to an American audience. Final Fantasy is just too Japanese for the X-Boxes primary fanbase. Even if it did well the most Square could hope for is 2 million MAX. The highest selling RPG on an X-Box system has been KotoR with 1.95 million, and when compared to how FFX sold 7.95 million, FFX-2 sold 5.21 million and FFXII 4.94 million so far, I dont see Square even trying to take a chance with Microsoft.
This is why Square-Enix hasn't given the 360 any real support because they know their games would sell horrible compare to how well they could be selling on the Wii and PS3. But now that the PS3 has crashed and is in need of a miracle the Wii is the only system that can give Square-Enix the sales they want. And it doesn't matter how underpowered the Wii is, if Square wants money they'll find a way to put FFXIII on the Wii. If they have to downgrade it like crazy, they'll do it, as long as they can get high sales that's all Square will care about.
Last gen proved that the system with the highest user base will get the most games, regardless of how powerful it is. If a company wants a game on the Wii they'll put it on the Wii, just like if they wanted it on the PS2, they found a way to put it on the PS2.