I really, really do not like the approach that Squarenix is taking with this. The guys cheering these awful business movements are the same guys that greeted the descension of the comic industry into huge, impossible to understand comic sagas and crossovers and that ultimately lead to its decline.
First of all, Squarenix is putting way too many eggs on the same basket with this. Why not get assured first that the original ffXIII is a great, popular game to beging with and then start with the sping offs, once people demands them, a la ffVII? This is selling the bear's fur before killing it.
Second, I really freaking hate the "if you want to understand everything buy everything" attitude that have installed into the Japanese entartainment industry (specially anime). A game with 3 spin offs it is not a story expanded 3 times but rather a story weakened so small portions of it can be sold onto separate products. Sorry, but I didn't bite that with Kingdom Hearts nor I am gonna bite it with this, thank you. I am fed up of insatisfactory endings and huge plotholes that must be solved by payng 50$. I simply cannot see why any RPG lover would be supporting such a thing.
Get your act together, Squarenix. Concentrate on the creation of new IPs that could substain you if your traditional ones fails, make sure your classic sagas keep strong instead of planning 14908 bajillion spin offs, and recover a bit of you experimental spirit during the 90s where you made some awesome non rpg games like Ëinhander or Bushido Blade, please.