The Fifa Ballon D''or is given by votes from national team coaches, national team captains and I think one media representative from every Fifa country. So again, just look at last years results, how far Messi has been with his votes. You'll see that Christiano shouldn't have any chance there.
I think the ranking will be as follows:
1. Messi
2. Christiano
3. Iniesta
These days, looking at the voting system, there's no chance an Iniesta or a Xavi can win the trophy, as Messi and Christiano just shoot to many goals and make too many asists. The problem here is, that a lot of people look at basic and simple statistics just as goals and assists, even though Barca's game would be nothing without Iniesta and Xavi. Although they are the backbone of this team (together with Busi), there's no chance to win a Fifa Ballon D'or as long as Messi lives and plays.
What I'd love Messi to do once is not just saying that he dedicates the trophy to his friends Xavi and Iniesta, but also gives it to him in front of everyone