The communist party of indonesia is the third largest communist party in the world, with almost three million member and almost twenty million sympathizers, so the question is if somehow the communist party is able to either overthrow or become the ruling party in Indonesia, what would happen next, both for Indonesia and the international community
The communist party of Indonesia was actually a supporting member of Sukarno's government.
Is Sukarno still around as ruler of communist Indonesia or someone else? Although Sukarno leaned heavily towards the Soviets, he still had an independent streak. But if it is someone else, someone with stronger Soviet sympathies, the Soviets would have access to the naval bases of Indonesia. Lots of butterfly effect:
1) the newly-independent nations of Singapore and Malaysia, as well as Brunei, may face longer-lasting communist insurgencies
2) The newly surging Japanese economy would be at the mercy of its oil supply under a chokehold at the Malacca Straits
3) USSR bases in Indonesia means a bigger US presence in Northern Australia; conscription in Australia may last a lot longer.