First of all this is Motor Trend so not the best source for details. The Gen V V8 isn't much of a rumor and it's launch in the C7 is fairly common knowledge. It's the details on the direct injection and cam in block that are the real important stuff.
I wouldn't take the 5.5L part to be very accurate for the production engine. 5.5L is what the C6R races right now in the ALMS per regulations. The actual debut of the Gen V V8 will likely be in the C6R's in ALMS as a racing engine. Production based engines are going to be required in that sport. And thats a good thing for us. But it doesn't mean that a production Gen V will have to be 5.5L and I don't think it will.
Lastly if there is a performance V8 and a Camaro in GM's lineup at the same time you can bet there will be a variant of the Camaro that carrys the mil.