Regarding Obama, give the man some space. He is probably no more than Reagan 5, but he should be given an opportunity to show what he is at. His nominations spell the continuation of Reaganomics, I grant you that. But lets see... He still hasn't take charge.
Reganomics is clearly unsustainable, so, if he continues through that path, that will lead to the demise of the US as a symbol (a hard-right symbol, I mean). The ideological export of neoliberalism will stop. There will be no more arguments of: "Look, in the US trickle-down economics work, we should imitate".
The only real asset of the US, if they don't get their economics working is their military. And that I am afraid of: they've proven to be war-mongering and in a context of highly economic distress it might come to increased military use (nukes et al, which they've used in the past).
We'll see. But, the downside risk is what you say. It'd be nice if they could get a decade or so of peaceful co-existence with the rest of the world, and multipolarity rather than the unipolarity to which its elites subscribe as a dominant lens through which to view the world, under their belt before their economic system finally goes bankrupt under its contradictions.
We can always hope. Nil aon leigheas ar an ngra ach posadh