Game director Tetsuya Nomura has confirmed that Kingdom Hearts III will indeed include the return of the Gummi Ship. The Gummi Ship was your preferred method of transportation in the first and second games, but sort of fell out of the loop amid the pre-sequels, prequels, and remastered collections that are all the other Kingdom Hearts games.
Nomura confirmed to IGN at D23 Expo:
"We can confirm that we do have Gummi Ships in Kingdom Hearts III because it is a numbered Kingdom Hearts title. You can expect that to show up, but it has evolved. We can't say how it has evolved, it's a secret, but Gummi Ships will be in Kingdom Hearts III."
As IGN remarks, the Gummi Ship was one of the more criticized aspects of original game, so a few changes were made in the sequel, and we are absolutely going to see even more changes in this new rendition of the ship. Nomura also confirmed to IGN that Kingdom Hearts III will feature new magic tiers. Many fans may have noticed the "Blizzaza" skill in the Orchestra trailer released around E3, and Nomura confirmed that this is indeed an even more powerful form of the Blizzaga spell we're all familiar with, thanks to the vast array of Kingdom Hearts and Final Fantasy games that have included it.
"The background of the tier of the magic, up until now, only King Mickey was able to utilize the most powerful form of magic," Nomura explained. You might remember that Mickey cast the highest form of Stop magic (Stopza) in Kingdom Hearts 3D: Dream Drop Distance. And these new magic tiers will build on that. "It has existed, and then in 2.8, as Aqua becomes Key Blade Master, she is also able to control the highest form of certain magic," he added. "As you noticed, it is a higher tier of magic, and Sora is going to be able to use that in Kingdom Hearts III as well."
Kingdom Hearts III will be released for PlayStation 4 and Xbox One sometime in 2018. The newest world to join the series is Toy Story, which was announced with a new trailer at D23.
While the game isn't currently in the works for the Nintendo Switch, Nomura hasn't ruled out the possibility of bringing it to the Nintendo platform after the PS4 and Xbox One versions are released.