Man world government is likely some bunch of elitists out there dream but it aint ever gonna happen the idealogical, religious and cultural differences will never make it possible.
Also if you want conspiracy I will give you one:
1. The banks are crashing cause the oil is running out its that simple, America may owe this and that but if america still has its nukes, man power and rest of its toys not to mention whatever oil they still hoarding in texas for when everyone elses runs out. Oh yea of course theres more to it than that, and houses are involved and lots of other jargon crap on all news outlets around the world. At end of the day the fabricated, delicate and fantastical(cos alot of it just on paper, I only trust in gold bars lying in a bank that you can touch) world economy is based on oil end of.
2. China is probably buying america's debts up most likely so it has a bargaining chip once the yanks start complaining about its agressive pursuit of securing oil which btw that nutty nationalist, getting more powerful by the day country is actually doing diplomatically unlike <cough> <cough> Iraq.
3. Yes there will be another world war because once the good times dissapear, People turn to desperate solutions, Queue the next dictator wannabes around the world with radical foreign policies= WW3
PS> Some good years after WW4= Which is fought with sticks and stones.