I would debate the collectibility of both the Rabbit and the Omni (other than the GTI and Shelby versions, respectively, of which the Shelby is definitely the more desirable and expensive of the two). But that is not the reason why I will disagree that the Crossfire is destined to a low market value years from now.

Here's a test. Price out a mint condition Camaro (of the most recent vintage) with the 5.7L V8 and the six speed. Now, price out a Mustang that is comparable in terms of vintage, condition, and equipment. We aren't talking SS here, so that precludes any Cobras in the comparison. My guess is the Camaro is going to be the more expensive of the two. This, despite the fact that the Mustang was much more popular when new, and was never dumped. The reason? The Camaro (stock) is a more serious performance car than a plain jane 4.6L Mustang. It has another liter of displacement, another gear in the transmission, and a good dollop more hp and torque.

By the same logic, the Crossfire should be more valuable than some (not all) SLK's down the road. Why? A Crossfire coupe (with its stiffer body shell, better wheels and tires, and standard 3.2L engine whilst the Benz came standard with a 2.3L SC, and lower curb weight) is a better performance car than the Benz ever was. Better looking, too. The saving grace for the Benz will be the novelty of the folding hard top, and perhaps as you mentioned that three pointed star on the hood.