Example #1: Socialism is about 150 years old. In that time, it's been the Cleveland Browns of philosophies, losing badly almost everywhere. Are we watching its death throes with North Korea and Venezuela? Countries will still back into it over time as government grows like Kudzu until it strangles an economy and needs to be cut way back, but that's not the same as deliberately committing to socialism.
Example #2: Christianity overcame slavery. The idea that each person has equal value because they were created in the image of God may not be universal, but it was the foundation for the defeat of slavery over much of the world. Do we expect slavery to make a comeback? I don't think so. That looks like an evolutionary dead end.
Socialism is a lot like this.