We can easily deduce what system KH3 will be on. If all of the previous mainline KH games have been on the PS2, then it is clear that the next will be on the PS3. Now it could see an additional release on an additional console if the company sees a viable audience to sell it to, but it would be their primary focus to send it to the PS3 first since it was already home on a SONY console.
We can also easily claim that it wont be on the Wii for several reasons, first KH already spans and builds itself on having a certain appeal for flash, awe, and storytelling, there is no way a game of this caliber, especially the conclusion of a trilogy of games, could be on the Wii. And also Blu-Ray isnt on the Wii.
And for Sonic
WE know that Sonic will be playable as well as Tails and Knuckles.
WE also know that it will involve motion controls
We also know that it will follow the same rules that applied to those in the previous Storybook series on the Wii, Sonic and the Secret Rings
We also know that it will involve swordfighting
We also know that the worlds will be large and expansive.
Anymore info you need?