Well, it matters on which viewpoint (capitalism, socialism, communism) you think would actually succeed. Considering the USSR never actually implemented anything remotely similar to true socialism or communism, I always wonder why educated people still declare that socialism/communism has failed.
How about Khruschev actually implements real socialism in the country? Rather than the period of stagnation that came with his collapse and the rise of Brezhnev, the Soviet economy and living standard would continue their upward rise until they finally surpassed the USA. With better living standards, the government can ease up on the repression of the people (since the people won't mind living in the USSR anymore). This also involves the government easing up on small businesses, and only maintaining strict control over necessities of life (power, food, water, infrastructure, automobiles, etc). Then, after Khruschev finally dies sometime during the mid-70s, lets say, the one who comes after him is a technology-advocate who adopts a system for the military that, by the 1980s, becomes the "Socialnet," linking the world together as never before. The .soc domain names become, far and away, the most popular, with the .com domain names that come with the USA's adherence to the socialnet a distant second. The socialnet soon dwarfs Hollywood as a tool of cultural propaganda, and leads to a new golden age for the USSR. The USA does not collapse in the way the USSR did (the USSR had conquered various ethnic groups, and 80 years just wasn't enough assimilation time, especially with the hardships that the people survived under), but its influence in the world drops to about the level Russia enjoys OTL. The final blow comes when France and Germany, seeking to further the EU, withdraw from NATO after public assurances by the USSR to never seek aggression towards Europe. This starts a trend, supporting both by EU advocates and the powerful Socialist and Communist parties in Europe, and by 1994, most of Europe, save Great Britain, has withdrawn from NATO and joined the EU, which is well on its way to becoming a left-leaning superstate. Meanwhile, the USSR expands the Warsaw Pact to include Cuba, and from there begins the process of inducting several new nations in Latin America, all with assurances to the US that this is not an aggressive maneuver, but rather simple expansion. Indeed, the USSR doesn't need to worry about the USA as an absolute threat anymore.