I think you're referring to Gaikai, which is a service supposed to start sometime late 2014 to allow PS4s to be backwards compatible with some PS3 games. I'm not sure if the HD ReMixes will be included in the list. As a matter of fact, there hasn't been an announcement on any PS3 games slated to be included with the Gaikai backwards compatibility. It's still a bit early for that.
I'm pretty sure it was confirmed for 2014. Actually, I guarantee you it will come out in 2014.
Honestly, if I had to pick between showing a game in its (very) early stages, or an HD collection that is already full of content ready to be shown, I think the obvious choice would be option #2. Besides, there's always a chance for a surprise trailer (something Square-Enix did a lot of in the past).
effects .
And here's the second part: http://kh13.com/zenphoto/cache/articles/game-informer/january-2014/post-29086-0-95161900-1386112488_992.png
Found these on KH13.com. Small preview of KH3 from the January edition of Game Informer. Included are some interesting tidbits on the game's plot...
Nashida .
Darkrai .
Hamster .
Oran .
Terminal .
