Square Enix is "very interested" in the PC platform. They acknowledge that the Final Fantasy VII and Final Fantasy VIII Steam re-releases were quite popular. These titles were originally released on the PC in 1998 and 2000, respectively. They are now interested enough to bring the three titles in the Final Fantasy XIII universe to Steam that were Xbox 360 and PS3 exclusives. Also, the first title is launching for $16, $14.39 on pre-order, so they are not even gouging us with a full-price tag.
The first title will be available in two and a half weeks (October 9th). The other two are expected to roll out by Spring 2015. Also, Final Fantasy IV was released on September 17th. They are actually releasing them faster than most people can probably play them. The flood gates are open. In their Final Fantasy XIII news post, PC Gamer muses about the rest of the franchise reaching the PC, such as FFX and FFX-2. It would make sense. I mean, they released (or are working on) seven remakes, not even counting the two MMOs. That is already a large chunk of the main franchise.
Personally, I wonder if this is testing the waters for Final Fantasy XV.
Final Fantasy XIII is being released on October 9th for about $15, give or take a dollar.