I hope the SGS3 has a 4.6" SAMOLED Plus HD screen, a battery that's well into the 2000 mAh range, a single physical home button, Ice Cream Sandwich with a nicely overhauled TouchWiz interface, also quad core sounds delicious, a 12MPx rear camera with flash, a front facing camera that doesn't stink, data connection capable of 4G speeds, voice command that feels modern, and 32GB on board storage with 2 GB of RAM. All that would be amazing!
HOWEVER, my biggest hope is that the phone is NOT majority plastic. All the sexy specs I just listed would be somewhat diminished if they were found in a cheap looking, and cheap feeling device. Even though I'm a big Samsung supporter, I've always been a little turned off by their love for low quality plastic on high end devices.