A good article from Stratfor concerning the evolving doctrine of the United States. Regardless of who becomes president of the United States, this will be the style of foreign policy for the foreseeable future. Even in foreign policy, were the president has far more leeway on the course of action he wishes to take than in domestic policy, those actions are directed by real world constraint.
Given those constraints here is what you will see. Less overt military action in areas that are not of prime importance, and a more hands off affair during regional events; provided that these events do not fundamentally challenge US military and geopolitical hegemony.
The US will still be heavily involved in the world, however, it will be in ways that are not easily discernible for the most part. For nations that would rely on the US but are not strategically important, i.e nations like Georgia or even Taiwan, then this is unwelcome news. For nations that are very much apart of the US interest, such as Japan, the Philippines, or Poland, then the equation will only change in so much as those nations will receive greater military material support provided that the US feels that they are upping their commitment to joint military treaties.