>> Puranjay's claim here is almost literally "change will happen, and it will bring grief."

The only place he mentions grief (rather than "demographic change requires economic change") is at the very end, with "And any large scale shift in economic models comes with some grief, at the very least." Nowhere else.

Some grief. As a footnote. That's hardly quantified, and itself could be covered simply by the fact change is hard. Japan was forced into changing, and...it went fine. The US hasn't yet. It'll require adjustment, which will probably bring some unpleasantness as we all adapt. That isn't alarmist, which was my point.