The American Dream is what you want to make it. It is the idea that here, you can do whatever you want and have whatever life you want but you have to go out and get it. Some things, like credit cards, make it more manageable to achieve but it also has messed up the economy and our personal lives but spending too much money that you don't have.
I'm not gonna say its dead, but it has changed from the 50's dramatically with the likes of credit cards and other things that allow us to spend money we don't have. In the 50's people were happy to have just cars and jobs and working electricity. Nowadays, we take all of that for granted and only want more.