In sum: By the end of the coming decade, unless we cut federal spending apart from Social Security and the major health care programs below the unusually low share of GDP it is already projected to reach, stabilizing federal debt relative to GDP will require us to cut spending on Social Security and federal health care programs by about one-quarter, raise taxes by about one-sixth, or do some combination of those approaches. That’s the fundamental choice we face.

More...
The above is a summary of a presentation by CBO Director Douglas Elemdorf.

Reading that, you might think we do not face a crisis. But, trust me, it's worse than it sounds. Catastrophe is just around the corner.