For a fascinating and realistic exploration of what that might look like, I recommend Kim Stanley Robinson's Mars Trilogy. In the series, a longevity treatment

For a fascinating and realistic exploration of what that might look like, I recommend Kim Stanley Robinson's Mars Trilogy. In the series, a longevity treatment is developed that significantly extends lives. Beyond the strain on resources, there are the issues of older generations delaying progress by not relinquishing power (much like the current octogenarian U.S. congress) and other issues.