I think the major economic challenges the world faces is Oil, and negativity.
When it comes down to it, all money is is an exchange of services. What this means is that in order for money to have value, people must be able to do valuble things or provide vabluble goods. In terms of commodaties, I think the world is okay, we have quite a bit, but the large majority of businesses in developed nations are service based.
In order to propogate a service based industry, I think there must be economic growth in the system. Due to the fact that resources and space is plentiful in North America, I would guess that Americans will continue to be the denominator in consumer power.
I think that China will experience a real estate bubble soon. I think it might be good for them though. The reduced real estate costs would allow China's middle class to be able to afford them, and the corrupt rich will still likely be just as corrupt, and a little less rich.
I think oil prices will continu to rise until it reaches a state where it's equally or more profitable to mine shale oil. At this point, the oil production nations of the world will find themselves in a little bit of trouble. North America will likely have a much higher majority of hybrid/electric cars by then as well.
I think Youtube, and web-media will unite the world in ways never seen before. We will resist war between nations, we will take back control of our governments, and with religion dieing, I have quite a bit of hope for the future. :)