Well you all know where I'd be; taking a dirt bath near the barbed-wire fence in some prison yard, with the likes of Simon dancing on my unmarked grave...
I think a collapse of the U.S. would have been a disaster for the USSR because while neither liked to talk about it very much their economies were surprisingly integrated through trade and loans. Desperate American banks - and there's no such thing anymore as an exclusively American, German or British bank, at least on the scale that governments deal with - would call their loans prematurely to the USSR causing a worldwide panic and bank run. The Eastern European satellite communist regimes were all (except Czechoslovakia and Romania) heavily indebted to the West, and they would have gone belly-up very quickly. The USSR just did not have the funds to salvage them, as Andropov made clear to the Hungarian dictator Kádár in the early 1980s. Poland's economy was already in a free-fall by 1987, and Hungary was artificially staving off a major drop in its living standard for fear of a repeat of 1956 by spending money Budapest didn't have.
So there was an imperial realm teetering on the verge of bankruptcy, with the political center unable to help them and teetering dangerously close itself to economic ruin. The Soviet military was still quite powerful - the most powerful single military in Europe in 1989 - but even in the most loyal communist satellites its presence was resented and what's more Moscow was discovering like all imperial powers that maintaining armed forces in colonies abroad is a very expensive undertaking. The WarsawTreaty/Pact was a non-entity, from top to bottom a Soviet mechanism for keeping the operations of all the communist states complimentarily in sync with the Soviet Army. The only time any of the WTO's organs actually functioned was after 1989 when the former Soviet Bloc satellites needed a legal-looking way to extract themselves from Soviet military control. The WTO's only truly independent act was to engineer its own demise.
The communist collapse of 1989 was not brought about by political will, it was driven by economic reality and the Soviet Union's connectedness to the world economy by then would have left it extremely vulnerable to an American collapse.
The result: A far bloodier 1989 (on a scale worse than that of Romania in December), as the Western democratic model may have been discredited by a U.S. failure and therefore the extremists in Eastern Europe may have dominated the agenda. Riots, army reprisals, looting, local uprisings, severe currency devaluations, ethnic violence, lynch mobs, a massive black market for basic goods [moreso than already existed by 1989 in Eastern Europe
] etc. would have engulfed Eastern Europe and no doubt spilled into at least the western republics of the USSR itself.
God only knows what would have arisen out of the ashes; a new empire? Several small warlord-controlled statelets? A radioactive desert (after the unattended or battle-damaged nuclear power plants across Eastern Europe, all built on the Chernobyl model or older, went into meltdown)?
Sorry to sound so apocalyptic, the gizzard isn't feeling so well today, but Eastern Europe was already leaning towards economic collapse in 1989 and an American collapse would have just speeding things up dangerously.
"work, and repeat, communism is the way of teh present..."
...
?
