What specific hints? In interviews or the games themselves?
I will be thoroughly shocked if Toy Story, the infamous model of Pixar, is not included in KH3. I 100% expect it to to show up as a world. Fans have been dying for it and this would be the perfect game to finally introduce it in KH. Plus as MS said Disney and Pixar are pretty much the same company now, so legal hinders couldn't really prevent it from happening.
Monsters Inc would really fit in KH3 second to Toy Story.
Mainly Nomura saying he's wanted Pixar in the series since forever.
But mainly these two things:
Disney's "Toy Box" & Square Enix's Missed Opportunity - News - Kingdom Hearts Insider