Even at low rates of CPI and inflation, the growth is still compounding, so it's logical to assume that, aside from the occasional dip, government spending will be on an upward curve. Not to imply that all government spending is "ok", of course, that's another matter.
Anyway, what's important to consider is ability to pay, that's what is key. Can we, if the economy improves, we end a couple of wars, and our export initiative is successful, for some examples, could we expect revenue growth sufficient to pay down this debt?