US debt has no theoretical limit. Instead debt value is limited by the
   amount of inflation incurred.
   The way the US rents the finances from the FED is confusing and I'm not
   sure what it means for where the rent goes. Ideally, it just reduces
   the amount of USD in circulation.
   The US is not in the situation that it's rent outweighs it's income,
   and is therefore not killed. Even if it does it mostly means the
   government and people will have to adopt another currency that's not
   hyperinflating. Then wait for the USD to devaluate the entire debt to a
   payable level. (Note: something Bitcoiny would be a pretty good fit for
   many reasons)
   As for US politics, LOL WE'RE ALL EFFED