Hmm. Okay, I need to play with this more.
Specifically, the US will have to collapse first in this instance, with the USSR collapsing 2nd. How? Well, here's my attempt. It probably won't work, but we'll see I guess.
The Soviet Union prepares better for Germany, and is able to beat back the offense, as well as seize France. The Soviet Union also ends up seizing the parts of Asia that Japan took like in OTL. In this timeline, Pearl Harbor didn't occur(Japan decided the risk wasn't worth it) and therefore the USA didn't enter the war soon enough to prevent the SU from getting all of mainland Europe.
During the Cold War, the Soviet Union has much more bargaining power, as the USA never got the economic boost from World War 2, and slowly begins to collapse. It becomes more reactionary, eventually resulting in the USA to take on fascistic tendencies.
Eventually, comes the 1990s, a movement for liberation triggers in the Northern USA which results in the USA splitting into two. It effectively leaves the Cold War.
However, the USSR collapses itself soon after from issues regarding command economics, resulting in both powers collapsing entirely. Okay, this is all probably ludicrous, but... it's a start perhaps.
I don’t think you need a POD
that drastic to achieve your goal. A Soviet France would create many butterflies in Africa and Asia.
From what was discussed, what needs to happen is:
A) an intensified Red Scare in U.S. (leading to McCarthyism and increased military spending, eventually leading to economic problems)
B) U.S.S.R. being more successful
Both of these points have been discussed many times on this site. I would provide some links but I don’t have time to look them up.
Anyway, here is my take on the matter:
-As suggested in your
Korea turns into Vietnam thread, the Korean War is extended into Chinese territory. Eventually though P.R.C. manages to push the Western forces back. Korean War ends as a draw like in OTL or a Communist victory.
-In the wake of the war peoples Republic of China and Democratic Peoples Republic of Korea join the Warsaw Pact to guarantee their safety. The Sino-Soviet Split is also butterflied away (lets say Mao is injured in an American airbombing during the war and dies a communist martyr a few years later). Their alliance with China and a lack of a large-scale divide in communist movement gives U.S.S.R. a boost it needs to stick around longer.
-Failure to unifying Korea under pro-western government and the expansion of the Warsaw Pact plays into American Red Scare. McCarthyism gains popularity. “Communist sympathizers” are rooted out and any organizations seen as being leftist are curtailed. More and more focus is put on military production and development.
-Eventually U.S. enters the Vietnam War. A more militant America achieves victory there – but it’s thought the use of nuclear weapons. This outrages the Warsaw Pact and brings the world close to nuclear war (maybe this could be in the TL a kind-of counterpart to the Cuban Missile Crisis?). The move alienates U.S. allies who see U.S. as nearly dragging them into nuclear Armageddon. N.A.T.O. shows signs of instability as an organization.
-With it’s allies abandoning it left and right, a growing debt due to military spending, more and more problems with ethnic minorities demanding civil rights, things don’t look so good for the U.S. of A…