I honestly think Sammy will make the or already have made the successor to the Nexus line, but I believe that leak is FAKE. The word Nexus Prime was so forcefully used. Oct is almost here and Google will show off IC and hopefully the phone as well.
I have a feeling it'll be later then Oct. It could be but if we don't see heavier leaks of images and other rumors/info of the Prime next month which is a month away from Oct, then I think it'll be out in Nov-Dec. That's about the same timing of the first Nexus and Nexus S. Then again, Google's yearly new UI and other things are revealed around Oct so yea, it could be Oct. Not to much longer of a wait..
I can't wait to see the phone, but one thing that will make me very happy behind the announcement is having it launch on every carrier that already carries a Nexus phone and Verizon. Even if it's a week apart but all in the same month I could dig it. It would only be proper and smart to compete with other phones that are on several carriers. They messed up sale wise with the first one and then late to other carriers with the last one. What will they do with the Prime III?