I think the lockdowns could be revealed as a costly mistake and there is a great hubris among the well off in thinking that because they aren't struggling everything is fine.
But this is particular argument is unsustainable. A lockdown can have generations of consequences - what doesn't? - but it cannot be paid for by generations to come. It was paid for now, resources were reallocated and consumed.
The risk is more subtle. If a group of people develop who have nothing to lose, then they lose nothing by being very violent and destroying stuff. Physical destruction of assets is something that can cause long-term damage. The lockdowns take away options from people who don't have many.
There isn't a reason to think that the US taxpayer is going to pay back their debts (in real terms). The numbers have gotten large enough relative to GDP that they aren't realistically going to honour those promises.
It may get ugly, but that debt isn't going to last generations.
The biggest loser will be the (US) general public, because it holds the majority of the debt. Foreign adversaries (such as China) hold a much lower percentage of the debt (and USD-denominated instruments).
Seems unlikely. Nobody makes reference to poor behaviour by someone's father's father when deciding to lend.
And it is already embarrassingly obvious that the US isn't actually going to pay their debts back. The people taking on the loans at the moment have hopefully accounted for that.
Is all this debt bad? Yes. Will it affect the prospects of future generations? Only if it spirals into a war and something spills over into the physical world destructively.