Doubtful. Just because it looks like it was made this generation doesn't mean there isn't room for change.
They already updated textures and models and whatever else they could. Too much change and it wouldn't even be the same Kingdom Hearts. The fish face is annoying but it didn't hurt in 2002 and it doesn't hurt in 2013. If this WAS a game made in 2013, it'd be a different story but it's still only a remaster.
Though things do happen a pot quicker these days.
Not really...tell that to Japan where they horde games for a year or more...Or even to North America and Europe where we still have a few months gap in between releases despite being in the same language.
The wait is done to align with the new school year where parents will be most willing to spend money on their children or reward them for school accomplishments, and to lead well in to the holiday season.
I just checked to see if this trailer was on PSN yet and it's not. No surprise there. It's an E3 trailer so it'll likely go up with all the E3 material.
It's a leaked trailer. It shouldn't have even gone online today but somebody screwed up.