(i haven't read the thread so if i'm not making sense please ignore me)
even if the us economy crashes and burns it will still recover eventually. Obviously replacing the current system is going to take an immense effort from both the government and companies involved in this but it's far from impossible.
I even think the hydrogen economy isn't such a bad idea. Obviously we will need to invest in new technologies to support this. But any change requires effort and money and obviously the current reliance on oil isn't going to get us anywhere in the future.
Fuel cells for cars would be a good start.... The PEMFC is a very good candidate and delivers an amazing 60% efficiency vs something like 20% in the combustion engine.