From what I've heard, Square Enix have announced a "KH3" project but not confirmed it. Coded, Birth by Sleep and 358/2 Days are subsidiary titles spun off from KH2. They are stories moreso in to Organisation XIII and times before Sora became Keyblade master. Apparently, they are all due for release towards the end of the year. These games were already well in production probably in tandem with KH2 so while we were loving the Disney/Final Fantasy clash for a second time, Square Enix were already working on the 3 titles for portable consoles. Given that fact, if a KH3 project is in production, it's liable to have been in the making quite some time ago.