Why do people think that the era of the US being a major power is over?

Anyone think this is bs? I mean from what I'm told and what ive read, some countries around the world prefer the US to be the dominant power. Anyone think this whole 'rising china' is a bit of an exaggeration? Sure there economy and military may be expanding, but who would follow China, or Russia for that matter? I just think that since the US economy is still recovering people are stressed out and are not being optimistic. Personally I don't see the world functioning without the US.