The USA does have at least one very vital export, and it does require dry bulk shipping. It's called "food", i.e., grain, corn, and wheat. The Chinese, and a lot of other countries don't produce enough to feed their own population. Maybe that's what Obama was getting at.
The question matters because bulkers don't typically carry finished goods.
There there is the question of whether additional ships would even be needed. Assuming no net growth in overall world consumption, this is a zero sum game. The same # of ships would be required. Just travelling between different ports or in different directions.
There's no apparent catalyst here to stimulate demand for increased tonnage.