Ok, I really think this is a smart move by Microsoft. A free game is a free game, and its a new game as well.
However, what matters most as to whether this free game will be successful in moving Xbox One units is the release dates of each system and Fifa itself.
Right now, it looks like Fifa is releasing on next gen systems on September 26th in Europe. If the PS4 releases on October 21st as rumored, then PS4 console owners could pick up Fifa to go with their new PS4 for a price cheaper than the Xbox One with Free Fifa. If the Xbox One is not going to release until, for example, the second week in November (we dont know, but MS said November so I am picking the middle) that would have given gamers in Europe nearly 3 weeks that they could have been playing FIFA 14 on PS4 before the Xbox One even came out.
So the big question is, will gamers decide to wait on an Xbox One with a free FIFA 14 for about $40 more or would they rather get FIFA and a PS4 for cheaper and own it approx 3 weeks earlier? I wonder if gamers would be willing to wait a few weeks just to pay more and get a Free Fifa, or whether they would want to play it NOW.
Of course, including FIFA for free would be a huge move if both systems release in Europe at nearly the same time. Many gamers wouldn't have a problem waiting 1 week instead of 3 weeks.
Now, for the countries where the Xbox One has been delayed in Europe, I dont see a Free FIFA helping anything. I do not believe gamers are going to wait 3-4 months to buy an Xbox One with a Free FIFA when they could have been playing it on PS4, for cheaper, for months.
I think the people this will help the most are gamers that are considering both systems. You can now go ahead and buy the Xbox One, so you can capitalize on the free game. If the system comes out later than the PS4, then you wouldn't have to buy FIFA on PS4 and could wait a bit until the system comes out to play it. Meanwhile, you could get your next gen gaming fix on a PS4.