I know Gates is incredibly successful, but what makes him think that his success in business and computers makes him qualified to be the authority on what type of world government the planet needs? America is a pretty diverse place, with 300 million citizens, and look at the level of disagreement and political vitriol that exists here. How much more dysfunctional do you think a world government representing 7 billion people would be, where the majority of government on the planet has corruption as a central tenet of its existence? I think it's so unworkable that not only will it never be possible in our lifetime, but it will never be possible PERIOD.
It's because the majority of government on the planet has corruption as a central tenet of its existence that it is possible, nay probable. They will claim they have the consent of the governed, when really people just have a self-preservation instinct, not willing to roll the dice in a global guerrilla war or get moved to the front of the line to the ovens.
I don't live in the United States so I can testify to this. Where I'm from, even among professionals, there is a shared understanding that to secure a certain standard of living one must align themselves with the big banks, the government, big phone companies, the media, the hospitals, the energy companies, or whatever. Outside of the United States there are fewer individuals per capita that have established themselves so that they are not tied to cartels - so to speak. If a larger state structure gets proposed, fewer people in other countries actually have the freedom built up to oppose it.