Platinum doesn't own the games they work on, they had as much profit from it as they did from Bayonetta and the TW101 Spirits, which is none.
If you want proof of that, just look at the trademarks in the website, they're not listed there even though Game Freak and Monolith Soft. are.
What does this have anything to do with them not wanting to share profits with Nintendo and Disney? Because if this really was a case of one or the other and Nintendo asking for one of their characters, Square won't profit as much from Sora as they would from others that are exclusively owned by them. Even more likely they wouldn't gain anything from Sora other than marketing as they don't own the KH brand. And I doubt Disney is one to be kind on sharing royalties.
Because Square could realize that Sora despite sharing profits still would make them the most money. Let me put this into perspective with financial figures to further illustrate my point. Kingdom hearts has a total of 24 million in sales so far. This does not include Kingdom Hearts 3 that will likely push the franchise right behind Final Fantasy in sales. Kingdom Hearts 1 has shipped 5.6 million copies world wide, and 1.5 million copies in Japan, and 3.0 million copies in North America. By October 2013 Kingdom Hearts 1 has sold more than 20 million copies worldwide.
Lets compare this information against the competition:
Dragon Quest itself has 75 million in profits so far, thats 51 million more than KH, which is significant I admit that.
However 75% Dragon Quest 11 sales came from Japan, which clearly states the majority of Dragon Quest fanbase is in Japan, and therefore not globally popular.
Dragon Quest is not a globally popular franchise, and does not match how Square does deals. All recent cross promoted picks are globally popular and in Dragon Quest's case you will be dealing with 4 companies and Sugiyama, which is way more than Disney, Nintendo and Square.
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Super Mario RPG, is not amongst the most popular Square games, nor among its most profitable. Geno is not recognized as the top 5 Square characters and he has not had a recent game since 1996, thats 22 years ago. Also Square is not like Nintendo, they do not try to appease fans by putting legacy characters as their cross promoted picks. As we would have Warrior Light instead of Noctis in Tekken 7.
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Sephiroth, would fit the fact that Square chooses FF picks as their cross promoted picks exception 2B. However they do not choose the same series twice in the same game. And it would make more sense since Cloud is already cross promoting FF franchise in Smash. They will choose another franchise to help them cross promote that franchise as well.
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Crono does not match the rules Square follows when it comes to cross promotion. These rules are the following, they help Square cross promote and help them make both long term and short term income. They as a character represent the company. And they are still relevant.
Crono would only help represent them as a company, but he would be able to help Square do what they love, which is cross promotion. Also he is not still relative as his game was released 23 years ago and has not had a sequel. He is in a similar boat as Geno, as Square does not prioritize legacy characters over recent characters.
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In conclusion despite sharing sales with Disney, Square still has the highest possibility of making the most income both short term and long term with Sora. Aside from Cloud he is the next most globally popular character, and would help them achieve sales globally and not just in Japan. By choosing Sora they are choosing a safe pick, because they know he will sell and not have a gamble like a DQ character. And of course they can cross promote off of him, more than they could with any of the other characters. Also again you underestimate Disney, I have seen a lot of Disney bias on this forum. And that is mainly due to mis information and not wanting Disney anywhere near video game companies. Nowhere is there concrete evidence that Disney is this giant that gobbles up the majority of profits when it comes to the games they make with 3rd party game companies and leaves little for their game partners. If this were the case then why do these game companies continue to work with Disney? Not only is Square Enix making a KH3, but an Avengers game. Also nowhere is it shown that Disney does not share profits when it comes to merchandise. Everyone really underestimates Disney when it comes them being persuasive, there is a reason they are the biggest media company. Bob Iger has helmed the acquisitions of Pixar, Marvel, Lucasflms, and FOX. All of these seemed impossible that Disney would be able to acquire and yet they did. Also he and Alan Horn convinced Sony(a rival company) to enter an agreement with them so the MCU could have Spiderman. Finally in Wreck it Ralph 1, Disney convinced several game companies to partner with them, and this included Nintendo and Square Enix. I really would stop pushing Disney as the boogeyman thats out to get profits and nothing else, because thats just not how Disney works. They have survived and thrived this long, due to the fact Disney knows how to negotiate. Disney knows when it comes to deals, they know what time is right push and when its not the right time. And they have also survived and thrived this long, because they know how to build good relations with other companies.