[marcosdumay]

It's not unsustainable if that's your question. There's no mechanism that automatically turn this into some clear case of failure.

As a consequence, "what is the solution?" will get sidelined by the question of "should we even solve anything?", even though high interest rates are clearly damaging.

On the actual question of how to solve it, I don't have any answer. Both austerity and inflation come with side-effects that may or may not increase that rate even more.