In an interview with IGN, Kingdom Hearts series director Tetsuya Nomura discussed new tiers of magic present in Kingdom Hearts III. When asked about "Blizzaza", an ability first revealed in the Kingdom Hearts III Orchestra trailer, he stated that it is indeed a more powerful version of Blizzaga. This was featured in the latest Kingdom Hearts III D23 2017 - Toy Story trailer, along with other similar higher tier magic abilities such as Firaza and Thundaza.
He is quoted below:
"The background of the tier of the magic, up until now, only King Mickey was able to utilize the most powerful form of magic [which was "Stopza" in Kingdom Hearts 3D: Dream Drop Distance]. 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. 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."
Nomura also talked about the return of Gummi Ships in Kingdom Hearts III. He reiterated what he stated in a previous interview with Game Informer:
"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."