The global goverment under the conditions that are now in force would probably be a disaster. However........
Towards my opinion liberal capitalism will collapse sooner or later because of its chaotic nature, arrogance and the fact that the planet simply can't take this forever.
What opens the question what comes after a liberal capitalism ?
At this point it is fairly obvious that undeveloped countries will just continue to experiance population rise untill they reach a tipping point. After that most of them will simply starve to death. What will leave the rich world without a fair amout of resources that were collected by those poor people and global economy as we know it. What open a number of possibilities. (like global government)
However global goverment is not as bad concept as it seems. (if done right of course)
Just because there is a global government that does not mean that you can't have a private company. Actually in this case there would trully be a free marked in a way since all the borders would be gone.
Also we could cut worlds military budget over 90% since we would not need all those weapons. I mean, do we really need a 30 000 nuclear warheads on this planet ?
Also such a reduction would unlock trillions of dollars and a huge ammount of resources that could be spent on a quality of life on a global level.
What would certainly permanently reduce the chances of totalitarism to return the stage as well as the chance that today's politics of nonsense will survive.
I mean with global goverment the most basic rules of the game will change.
Also: Wall Street did alot of things that caused the current economic crisis. (I mean really stupid things) So my question is if you can tolerate that someone can effect your life like this, then why it is a problem if a global government is doing something similar ? Especially since with a global government you can have some effect on the decisions, plus there will not be the entire "business secret" thing that is persent on a Wall Street.
Also there will be so many eyes pointed at that goverment that any case of corruption is less likely by default. (maybe even impossible)
I am just thinking out loud.