Kingdom Hearts was not originally conceived as an action-RPG. Nor was it originally focused on a battle between the forces of darkness and light in people's hearts. An epic franchise of games across multiple hardware platforms was never planned and Tetsuya Nomura has no bible that dictates all past and future narrative events. These are facts and unless you believe them I won't be able to talk sense into you on the franchise trajectory of Kingdom Hearts.
Once upon a time, two prolific producers discussed a colorful game that would have a free range of movement similar to that of Super Mario 64. A studio contributor with noted potential overhears this conversation and volunteers to direct. Serendipity places one of those prolific producers in the same elevator as a Disney Japan executive and a pitch is made: an action game that stars Disney characters, appeals to kids, is action-oriented, and developed by Squaresoft.
The nonsensical story and motifs the franchise is now well known for were late additions. The developer couldn't acquire the IP rights to the word "Kingdom," a reference to Disney's theme parks, so the team looked at incorporating the concept of “the heart” as a core part of the story. The former prolific producer, Hironobu Sakaguchi, told a younger Nomura that the game would not succeed without a story that reached the same heights as Final Fantasy. Had these events transpired a little differently we would have likely seen something more akin to Disney's Magical World. Instead, original characters were introduced, Final Fantasy heroes made cameo appearances, and Disney locations set the stage for one of the most obtuse darkness vs light plots to ever grace a JRPG.
There would have been those at Square who didn't expect the game to be a success. Kingdom Hearts was lead by an untested director, featured two very different worlds and gameplay that didn't resemble any of the developer's previous efforts. It's something of a miracle that the game took off the way it did both in Japan and in international markets. How would this darling release be followed up though?
Instead of jumping right into Kingdom Hearts II, a game which would take place a year later, the development team looked to the GBA. A smaller game with new plot elements would bridge the gap between Kingdom Hearts and its numbered sequel. This is the first point where the narrative consistency of the franchise is thrown out into chaos; in order to provide some narrative reasoning for Sora et al starting from scratch, again, the theme of “memory loss” was added to the plot. The gameplay was altered drastically to better leverage the hardware and Organization XIII made their grand introduction.
Without having played Chain of Memories for the GBA you would not have understood what was going on at the beginning of Kingdom Hearts II. Which was the case for most players. Kingdom Hearts II shipped approximately 4 million units by the end of 2007, whereas Chain of Memories had sold a total of 1.5 million units by the end of 2006. More than half of those who purchased the sequel had no inkling of the plot elements that tied Kingdom Hearts II to the original game. They may have also been confused as to why Sora had been placed in a coma, what would have happened to the other half of Organization XIII that isn't in Kingdom Hearts II, and who the hell Naminé was.
All of this was foreshadowing for the years to come, as Kingdom Hearts III would be pushed off again and again in favour of spin-off after spin-off; further confusing series chronology by introducing narrative elements and characters that had little-to-no bearing on the initial plights of Sora and friends. Many of those narrative threads have been tied after years of piece-work sequels, but that actually highlights the big issue that is threatening Kingdom Hearts III's success.
To what market is Square trying to sell Kingdom Hearts III? The gamers who can afford to buy six different consoles? The two mainline entries have had the most reach in the market, and it should be noted that the sequel sold considerably fewer units. It would be a fair assumption that Kingdom Hearts III hasn't been continually pushed off because Nomura needed more time to put an ending together; it's been delayed because such a big production was a serious financial risk for Square.
Here's the catch-22 Square has been wrestling with: it was the financially sensible decision to greenlight smaller titles that pushed the Kingdom Hearts brand, but in order to do so they had to further complicate an already bloated narrative which had been built upon relatively shallow themes. Without buying repackagings of all of the previously released Kingdom Hearts games most gamers wouldn't have the wherewithal to understand what's going on in this dense, epic poem of a JRPG franchise. And boy, has Square ever been pushing those HD remixes.
The latest monstrosity to be released from the Square-Disney hydra is Kingdom Hearts HD II.8, and it includes an HD remaster of Dream Drop Distance, a movie detailing the events of Kingdom Hearts X (pronounced “kai”), and Kingdom Hearts 0.2: Birth by Sleep - A Fragmentary Passage. Excusing awful naming conventions, I would be remiss in mentioning that understanding of 0.2 requires that the player have completed Birth by Sleep on the standard difficulty or higher (events tie to one of the game's secret movies). If Kingdom Hearts HD II.8 is needed to understand Kingdom Hearts III and I.5/II.5 are both needed to understand II.8, what we have is a narrative catastrophe that also represents a huge barrier to entry for new players.
Ultimately, my concern is that Kingdom Hearts III will be a financial failure to some degree due to the narrative obstacles Square and Nomura have introduced over the past decade-plus of micro-sequels and Final Mixes. At this point it's hard for me to imagine Kingdom Hearts III being coherent enough for outsiders to understand or want to buy. Which won't be a problem for series enthusiasts who take pride in understanding the pig slop that's trickled out over the years, but doesn't spell good things for the future of the franchise.