This happened twice in Smash 4, with Roy and Ryu being revealed simultaneously, and being released right after (with Lucas), and with Corrin and Bayo who were revealed together, and released together two months later.
However, that doubling (and tripling) up was allegedly due to the technical limitations of the 3DS whereby it was most cost-effective to do fewer updates.
This time only Hero and Banjo have been revealed during the same presentation, though obv they weren't released together.
A dual release seems quite unlikely when you consider there's about two years in which six characters will be released.
Sakurai said that Lucas, Ryu, and Roy were released at the same due to 3DS titles only being able to be updated a set number of times, so I don't think it'll happen again. Released when revealed though, I could see that if they wanted to do it again.
I still couldn’t see him without Disney characters showing up in some shape and form...as a non-KH fan it seems weird to me regardless of whose words I’m supposed to take
Whenever Sora appears in a non-Disney crossover, he never appears with other Disney characters unless they are also Kingdom Hearts original characters.
World of Final Fantasy
- Appears in his Dream Drop Distance form.
- Only Sora appears.
Final Fantasy Record Keeper
- Appears in his first Kingdom Hearts appearance with KHIII as a costume.
- Appears alongside Riku (KH, KHIII), Roxas, & Axel.
- Cloud & Squall receive their costumes from the first Kingdom Hearts.
Final Fantasy Brave Exvius
- Appears in his first Kingdom Hearts appearance.
- Only Sora appears.
- Another Cloud in his first Kingdom Hearts appearance appears.
The only non-Kingdom Hearts Disney thing in any of these crossovers is the Hidden Mickey that serves as the Kingdom Key's keychain.
This shows two things..
1) Disney doesn't mind licensing out Sora (yes, they are all Square-Enix titles but I doubt Disney would deny Nintendo given how big a name they, and Smash Bros, are).
2) Sora can appear without any non-KH Disney characters just fine.