The upcoming Final Fantasy XV is scheduled to come out sometime this year for the PlayStation 4 and Xbox One. And as a sharp-eyed NeoGAFer noticed, it might be coming to the PC too! Then again, it might not. The truth is, we don't really know. But there's a pretty good reason to think it will.
But the excitement was diminished somewhat when another user noticed that the code in question was essentially a copy of code used for the Rise of the Tomb Raider page. That led to the theory that the whistleblowing code was simply copied and pasted to the Final Fantasy XV site for convenience, and that the Steam reference—since Rise of the Tomb Raider was released for the PC—was simply a bit of overlooked detritus.
As far as I can see, the references to Steam (and other platform stores) have since been removed, which makes the situation even trickier. Personally, I'd assume that FFXV will eventually make it to the PC, sooner or later, but that's based solely on recent history and the fact that there's no good reason to keep it to consoles, rather that anything Square Enix has said, done, or even hinted at. I've emailed them to ask and I'll let you know if I receive a reply; in the meantime, keep your fingers crossed.