Slower and steadier liberalization perhaps?
That's what I'd go for, too. Perhaps Stalin's excesses result in a steady liberalization starting 1954-55, leading to first the end of strict communism into more socialist capitalism (accomplished by mid-1970s), followed by increasing freedoms for people.
However, freedoms stop with nationalist idiots. Trying to undermine or destroy the USSR will still have VERY serious consequences. (Read: a bullet in the head.) This would result in likely economic growth in the USSR through the 1950s and 1960s as in OTL, but it wouldn't stagnate as it did in OTL, instead keeping on going through the 1970s and 1980s. Think China today for a good example of what to expect.
By the mid-1980s, prosperity has truly come to the USSR, though the USA still regards them as the "Evil Empire". Both sides spend substantially on their militaries in an escalating game of chicken, and one that doesn't fall off in the 1990s. A much bigger Soviet economy allows for its outrageous military spending without destroying the economy. By 1995, though, both sides realize the costs are too much and start to ease off somewhat.
Through the Cold War, the Soviets continue to support many groups all across the world battling imperialism and American hegemony. The USA does the same except in reverse. After Vietnam and Afghanistan however, neither side is terribly wishing to commit its own people to such battles, so the "proxy wars" rage around the world through the 1980s and 1990s, and some flashpoints last considerably longer than in OTL - South Africa/Namibia/Rhodesia, Iran/Iraq, southeast Asia, pretty much all of South America.