Like Tales, most of the main games are stand-alone. Only ones that have sequels and/or prequels are FFIV (sequel), FFVII ((two prequels and 1 sequel, and one (or two, but it's same and remastered) sequel movie)), FFX (sequel, and one rumored sequel to the sequel with a hinted FFX-3), and of course FFXIII with the trilogy.
The DSi was released in 2009? Go change your pre-order! KHIII is now on PS4 instead of PS3! Does the store you pre-order it at even still have it on their computers? I mean there are people who pre-order games clearly a year before the game is supposed to release, but 5+ years now? Do you have your receipt at least? Then you can be like the Duke Nukem Forever guy who waited over a decade, and get free swag when the game finally comes out lol
I wish they would have hopped on to PS4 like Atlus did with Persona 5. Their target is the Japanese audience who clearly are still fine on their PS3s, but the western market audience has greatly shifted to PS4 now.