Yes, considering the huge popularity of FIFA series in Europe, or BF around the world it would be a true game changer.
But it will not happen imo. Nowadays, the idea of any type of potential exclusivity from a company like EA is delusional, a minor partnership though, would be logic, that´s all.
Why do people keep saying this like FIFA has been a juggernaut for decades or something?
EA has had a massive licensing advantage for a long time now and it wasn't too long ago that Winning Eleven/Pro Evolution was eating their lunch in Europe and Asia. The change to the PS3/360 generation is really when EA was able to turn the tables, as Konami failed to step up the quality of their game and EA actually worked to make a good title.
EA still views WE/PE as a legitimate threat, hence why they constantly bring up FIFA v. WE/PE sales now that they're on top. The last thing they'd do is take a predominantly European/Asian franchise and not put it on the strongest console in those regions.
Hell, Winning Eleven was still a million seller on consoles in Japan this generation and that is with FIFA gaining on them. MS isn't delivering them Japan and there is clearly six figures or better in new software sales to be gained by taking that market from WE as well.
Exclusive DLC in Respawn's new game? I could see that. Maybe even Battlefield (though doubtful, as that would weaken their cross platform war with CoD).
Madden is highly doubtful (the license is up after 2014, the NFL won't renew if EA isn't pushing the NFL brand uber ales). FIFA is a non-starter.
Other than that EA doesn't have much of note. Bioware's next game as a full exclusive is the best MS could probably land because Bioware's declining game quality got massively exposed when it was no longer judged through the "platform exclusive" filter.