First of all it's not just the US but the entire world. Trick is, as always, simply not to do worse than others.
As for tens of millions being unemployable... so what? What are the practical problems it creates? Crime? Highly unlikely. These people are older and more individualistic and serious property crime is a collective affair. Crime is low these days in general so even a considerable increase in it won't be some sort of unmanageable disaster, America has been there before.
I can't think of much else in terms of problems it could create.
Consumption and thus "keeping economy going" is currently maintained by people who make income from capital and it will only become more so. Employment as a tool of distributing money for consumption will simply become less relevant.
For next generation, it will be easier because surely personal service will get revived as a mass occupation - and there, having a person is the whole point so it's safe from automation by definition.
You need not look further to find your first "practical problems"
It did not happen because of sudden productivity increase that put too many people out of work. No economic crises ever happened that way, and there is no reason to believe any will. This is what every economy strives to achieve and it's kinda stupid to be afraid of it. Some people can be hit hard, and it always happens during every technological revolution, but with sufficient investment into predictive policing and law enforcement overall, this is a manageable risk.
Surely, a stock market shock can happen other way around - if AI will turn out to be a flop - but i believe this is not the risk you are talking about.
Look at what happened during the Great Depression, when unemployment was high. It doesn't matter how we get to high unemployment or depression status, but for sure there will be a lot of bad things, many more than you proclaim.
Look to the Great Depression to see what the human condition and spirit was like if you are having trouble imagining possibilities
But we are speaking simply of mass unemployment. That alone is not enough to cause widespread despair.
I think a simple question, where do the unemployed eat and sleep during extended, high-unemployment?
Are breadlines in 21st century America not a thing you foresee in a 21st century depression?
Cops kill almost daily with immunity.
Spouses across world abuse each other and their children.
You rely on slave labor so you can perform useless IT work.
But no one ever acts so uncivil as I have on HN.
Oh look another ...old... account. That explains the Mr Rogers-like-view-of-reality.
Thoughts and prayers.
How many accounts have you had? How many have been banned?
yes, I'm still on my original account I made when a college roommate told me I needed to be on HN
Your post is not the sign of someone who is healthy either, people don't say things like you just have.
Nor is it the level of discourse HN finds acceptable
HN is a bunch of ostriches
Thoughts and prayers!
Crime is low where income is adequate, Crime is (very) high otherwise