The U.S. Marine Corps has had to cut training time since September 11, 2001, because troops were so busy with counter-terrorism missions, especially in Iraq and Afghanistan. One skill, in particular, was allowed to atrophy; amphibious landings. In the last decade, only about seven percent of marines maintained their amphibious landing skills. Now that the marines are out of Iraq, and not as many are needed in Afghanistan, more amphibious training will be possible.
Marines will also be able to catch up other special training, especially for commando, conventional warfare, civil affairs and peacekeeping type operations. Experience in Iraq and Afghanistan provided lots of practical experience in "peace making", but peace keeping is different in some important way, and there are a lot of other specialized jobs marines can be called on to take care of.
Marines have acquired valuable combat experience in Iraq and Afghanistan, that is useful no matter what type of operations they train for. Even Iraq and Afghanistan are very different in many ways. Having experienced combat in both places makes officers and NCOs particularly well prepared to participate in other types of combat operations. The marines discovered this during World War II, where thousands of NCOs and officers found their peacekeeping experience from the 1920s and 30s useful in the Pacific, even though that was a very different kind of war.