They had to loose market share. They introduced several, at least visually, appealing cars (the big Ram pick-up, the 300, and the mid-size I forgot the name), and then nothing new. How do they survive now? Mini-vans and Ram? What do they offer as a mid-size entry (not many people will pay $35k for a boat like the 300, when you can choose from a wealth of Japanese semi-luxury entries)?
Should we all buy PT Cruisers, Vipers, or Neons? They had it too good for a couple of years. To me, they don't have any attractiveness. Just showing off in car salons. People got tired of people pushing silly designs.
Just look at the Nissan/Infiniti line-up. What's not good there? Give me a Sentra, even!