I had the very same idea expressed in Joe Klein's weekly column maybe ten days ago driving home from work: would President Obama ever let Robert Gates stay at his post at the Pentagon, if only for a couple of years? Klein focuses on the political aspect of the idea--it would indicate Obama's seriousness about bipartisanship from the beginning. There could be another benefit: one perennial problem democratic countries have in reforming their institutions is that leadership changes every four years. If a Secretary of Defense arrives intent on changing our military budgetary priorities, the Air Force generals addicted to new fighter jets that we don't need only have to stall a couple of years and voila! the problem disappears. Other examples of hidebound thinking abound (automatic budgetary parity between the three branches, high-level promotions favoring very narrow fields of service). Giving Gates another couple of years would give our military a much better chance of reorienting itself for the 21st century.
Matt Yglesias' rejoinder is that Obama leaving Gates around would send the message that Democrats are not as serious about national security as Republicans, an outdated narrative that Obama's campaign seems intent on disproving this campaign. Yglesias could be right, but I think Obama can have his cake and eat it too; if, as president, he were to run an exemplary foreign policy with Gates at the Pentagon, that would reflect well on the Democrats as a whole, and Obama wouldn't carry an asterisk around with him for having appointed a Republican Secretary of Defense. In such a scenario, I think voters would be more rather than less ready to trust a Democrat with our foreign policy in 2016 and beyond.