Since 2001, the US Dollar has lost half of its value every 4 years. Of course, its actual value dithers about, sometimes more than this theoretical value and sometimes less, but as you can see from the chart below, it tracks very close to this decay line. The chart below also projects this line into the future, giving a reasonable guess at what the continuation of the last decade's policies will do to the USD's value in gold terms.
Will these policies continue? There is no way to be certain; if debasement is pushed too hard, people may lose confidence, leading to a dollar collapse. But to reverse the trend would push interest rates sky high, and result in budgetary and monetary chaos as well. Thus a continued steady devaluation of the dollar is likely the "best case" central bankers can achieve.
I have added this page to the Charts section of the site under the heading Half-Life of the US Dollar so you can follow along and see how this prediction unfolds.