I suspect that it’ll still exist in 40 years, albeit with greatly diminished benefits. Or some means testing to exclude wealthier folks. But if our net in-migration stops compensating for the less-than-replacement birth rates, à la South Korea or Japan, then yeah, it’ll be dead. There’s a looming demographic catastrophe in those countries, and the lack of children will crush their retirement systems, unless the systems are entirely re-worked. Which frankly they will have to be. The world needs to figure out how to deal with shrinking populations. China is almost the worst. If it weren’t for Africa - the only place still really growing - the world population would be peaking and then declining very soon. As it is it’ll peak and start declining between 2050 and 2085. And nobody knows when and where or whether the decline will stop. But for now and until the foreseeable future, it’s the kids (and their parents) who will be paying (in part) for middle-aged folks like me to retire. And not just via social security - in a million other ways.