Kingdom Hearts 3 first teaser was fully CG, and it shows: it looks MILES better than what we currently have. Maybe the animations are a bit stiff (they probably ripped the ones from KH 2) and the environment looks pretty bland and empty, but current KH3 doesn't come close to the initial trailer in terms of character model (nor it should, as Sora's first model was straight-up CG).
The Leviathan fight huge downgrade has a good explanation (it was still pretty unimpressive and ugly in the final game, though: they could have done a much better job), and that's that the FF XV E3 trailer was incredibly touched up, with huge amounts of non real-time CG there, especially in the Altissia parts. The character models, however, look considerably worse: they really show their PS3 immediate past.
Let's see what they talk about in the ATR. I'm assuming a lot of it is going to be about the game's reception and stuff like that. I guess they're going to show tentative timeframes for the releases of the DLCs, and talk a bit more about them.