Car and Driver had a throw away line that started off speculation on the internet about Cadillac;

Cadillac fans will be thrilled to hear that Ed Whitacre himself has instructed the brand to build a true, full-size flagship above both the CTS and the upcoming XTS. The car has not been clearly defined yet. The Zeta platform (Holden Commodore, Chevrolet Camaro, etc.) is heavy and dated, and therefore the flagship is more likely be built on a stretched version of the CTS's Sigma platform.

It also included that a smaller Cadillac based on the Sigma platform (CTS) will be produced as well. I seriously doubt both of them really. Cadillac doesn't sell that much and the Sigma platform is unique to Cadillac only and was built in competition to Holden's Zeta platform. They both do the same thing, they are large car rear wheel drive platforms.

The quote says that Zeta is too old and heavy. That can't be true, it has newer and more flexible engineering than the Sigma platform. For instance the Zeta platform supports Holden's Commodore and Statesmen, as well as Chevrolet's Camaro.

The Camaro has been widely successful and knocked off the Mustang as the best selling pony and muscle car. It is interesting though, as Americans and the American media do not throw their cars around as much as the Australian and British media do, so good handling, a-la Commodore, is not as important in a US sports car.

Supposedly the Cadillac flagship will take on the likes of Bentley in the big ass-car with every gadget and piece of leather known to man included. They are big cars anyway. It sounds like a Cadillac person was sounding off a little too much about what they want to do and it has been presented as fact.

I was behind one of these the other day going up the 101. Their butt is so huge and so high that they look like a minivan from the rear. The photos you see of the CTS Coupe hide it, but the Cadillac has a ginormous and ugly butt. Not a pretty car at all.