Issues that I predict will dominate the 2008 US Presidential Election:
Bio-ethics (abortion, stem cell research)
The UN/ America's position in the world (not Defense issues, but rather how the US should act on the world stage, as in unilateralism versus doing whatever the UN wants)
War on Terror/Iraq/Afghanistan
Free Trade/Protectionism
More I am sure, but this comes to the top of my mind.