So let's say that the domino effect went a lot further than it did in reality and that after Vietnam finally succumbed to communism in the 70s, communism started to spread into Japan. Suppose more pro-communist rallies, protests and eventually violent riots broke out and eventually Japan fell to a communist revolution, which the Soviets quickly respond to by promising direct military intervention against any country that attacks Japan. I'm guessing that if this started up after Vietnam's turn red, Japan would fall around the late 70s, maybe early 80s. So what effect would this have on the Cold War and on history up to today in general?