Highly unlikely. Sony may do something similar to EQOA, the PS2 version of Everquest, but getting a PC MMO onto a Console platform is a logistical nightmare - the patches would quickly fill up the XB360's hard drive. In other words, it'd be a separate, different game.
Before anyone says, "Final Fantasy 11 is a PC MMO that's been ported to consoles!"... No. FFXI is a console MMO that's been ported to PC. There's a difference. With a console game (even an MMO), you've got a static, solid build that rarely (if ever) gets patched.