Sure it may have won them over in the U.S and possibly Europe but multiplats do better on the PS3 in Europe, however FFXIII not being released in Japan on the 360 is a huge loss.
Microsoft not securing FFXIII to be released in Japan for the 360 was their only goal and we all know that. They're trying to expand Japan, not elsewhere. So if Microsoft thought they won, they're in over their heads cause the 360 sales will continue to be less than impressive.
I sure hope Star Ocean 4 or Infinite Undiscovery and Tales of Vesperia (which only has a 50+k pre-orders now btw) proves that, no matter what JRPGs are released on the 360 in Japan, it just won't go anywhere and finally give up.