What’s going to happen with the US national debt?

I’m neither an economist nor a native English speaker and I have some questions after reading this:

https://finance.yahoo.com/economy/policy/articles/treasury-just-declared-u-insolvent-151425143.html

1. Is it accurate?

2. If Congress does nothing – which seems to be its thing – what will happen when the debt payments become unmanageable? A classic Trumpian refusal to pay and then what? Default? Restructuring?

3. How will different asset classes be affected?

Thanks in advance!