On the one hand, outward perception would indicate that the Wii would be a model home for a "family friendly" affair that would be Kingdom Hearts 3. Surely, Disney sees this.
And, with Dragon Quest X going to the Wii, clearly Square-Enix has some confidence in releasing major franchises to the system.
The other thing is, Disney really likes Sony--that's long been obvious. KH3 could still end up on PS3, but I wouldn't be surprised if it went multiplatform to the Xbox360 as well.