Good point about the aging demographic that aspires to own a Caddy. I once met a customer and we got chatting about cars: he had two DTS', but he was in his late 60s at least.
I think the CTS does a good job of putting Cadillac on the radar for many younger buyers. An entry-level car that competes directly with the 3 and C (which I hear is in the works) would help their case, too.
I think they also have a problem (slowly changing) with nobody buying the midlevel GM products. Cadillac should be an upgrade for buyers of the Malibu, Astra, etc... but if nobody buys those cars...