Earlier quoted context omitted.
"Things won't get interesting until B approaches D." I'd say things would get pretty interesting well before that point. B=D is just the point at which a default is inevitable (unless much higher tax revenue is achievable without causing other problems). But the problem is that the interest rates are so low now that large increases are not outlandish. 7 years ago, the rate was more than double what it is now. Looking…
Interest payments as a percentage of GDP are actually much lower now than they've been in the past: http://research.stlouisfed.org/fred2/series/FYOIGDA188S
And we shouldn't be surprised if rates go up substantially, because they are at historic lows right now.