“elderly people would be shivering constantly and highly susceptible to respiratory illness.”

At 66 degrees F? That sounds like put a sweater on if you’re chilly, not some near death extreme.

Any evidence that such an ‘extreme’ would cause issues?

It does seem like if I was China, this would be the perfect time to make a big geopolitical move: EU and Russia tied up with Ukraine and Iran, US & Gulf allies now stuck in a war zone, US showing aging tech with large exposure to new drone warfare.

This seems likely the conflict that forces the US into an immediate course correction in military makeup, or suffer large and expensive mass casualties on the battlefield.

What happened to Battleships after Aircraft Carriers entered the picture, comes to mind.