It's certainly not an oppressive dictatorship, but we get more authoritarian by the day. Patriot Act, indefinite detention, the authorized killing of US citizens aboard, TSA nonsense. I think Glenn Gleenwald put it best, authoritarianism in the US has to be handled piece meal, to get the people use to it overtime.
To a large degree that's true, and I'm quite happy I still very much have freedom of speech here. However I wouldn't say our political system is really open to scrutiny in terms of political power, it's largely designed to keep other views out, through restrictive ballot access laws, exclusive debates, etc.
Oh of course not, events are rarely carbon copied onto one another, and the US is different in many ways to the USSR. But I do think we'll be seeing a decline of the US within the next few decades, with rising income stratification, and with it declining living standards. Nothing like what Greer says though. No return to "agrarian" nonsense or whatever.