I agree with your premise, yet am not sure that the underlying root of the problem is our reliance on the growth is good.
One of the big benefits I feel and THE biggest problem with capitalism is creative destruction. As money and capital and ideas flow from one idea to the next, many things are created, and concurrently destroyed. People are laid off and people are hurt, but (trying not to delve into Soap Box here) all in all the products become better over time for a better price. As you mentioned our mixed economy, as we try to dampen the negative effects and harbor the positive effects of our mixed economy, we eventually start to overextend ourselves leading to a devaluing of the dollar. Issuing more dollars (some believe) can help the economy very short term. But, then again, you can't have your cake and eat it too. Many of our "pro-growth" policies are not incredibly pro-growth when you throw in all of the taxes, redistribution, deficit spending, printing money, etc.
It IS a matter of preference though, some would say who needs growth when we have 10+% living in poverty, yet there are tradeoffs to any situation naturally.
I just see this as the natural growth model. Those who are the farthest behind have the most room and the quickest growth. After World War II, the infrastructure that was put into the U.S. was unparelled in the developed world (what WAS the developed world?), and we grew for it. After our infrastructure of electricity, gasoline, roads, highways, schools, hospitals were all put in place, it became a matter of improvement, which would take longer than just plopping some roads in the middle of India. Point being, the greatest potential for growth is in the countries that are the farthest behind.
This does not mean that U.S. will become a third-world country. It means that if we continue to invest in our infrastructure and our future and have responsible leaders, we will continue to grow at a pace maybe not as fast as we originally had. What makes you think that most companies in the country cannot continue to post better earnings than the decade before? I am not so certain that it is impossible. Remember, we may not grow as fast, but last I checked, our GDP is barely below the entire E.U.'s