If we reach the point where global stability depends on whether or not debt by almost every first world country can be paid or not, we will be in a situation where we have to evaluate whether or not keeping that debt around is worth the risk of total economic collapse.

Consider - each country can either: a) mutually agree to cancel all debt (or some large portion to mitigate the situation, say 50%) or, b) continue to demand the debt, thus perpetuating the downward spiral of the global economy, thus ushering in an era of civil unrest and large civilizational changes.

I'm not trying to sound all doom and gloom, but I think a large part of the economy is very much "pretend money" that works fine with high levels of productivity and economic output, but can very much just be done away with if the alternative is total collapse.

The GFC wasn't a total collapse. It was just the loss of large amounts of profit for some large bankers. This had severe consequences for some people (mortgage foreclosures, jobs etc), but wasn't on the scale this article describes, or anywhere close.

It's a bit like the worries people (rightfully) have around foreign ownership of land, especially farmland. Yeah it's not ideal now, but you think private property laws will be upheld in war time? If a country ever goes to war with say, China, (a large owner of foreign farmland), you can bet that country will simply seize it all and repurpose it for the war effort before you can say "world war 3". Private property is nice on paper, but when push comes to shove it's just that - paper. Easily rewriten.