"It will work, people..."

It won't, for the same reason the euro isn't working. Each countries economy is unique and each operates according to a very individual set of parameters. For instance, Germany is doing well because it makes stuff and exports it, the Greek economy is totally different as they have very little manufacturing. What you end up with is a single power driving the economy and imposing their ideas on other countries. This is why the Greek people voted out the austerity-loving government; they are paying for the profligacy of their banks and rich folk and the Germans are making them do it.

The thing is, it will end up with one or a cabal of a few countries dictating global economic policy, and that is not only a recipe for disaster (given, for instance the fact the US has it's head in the sand over/is wilfully ignoring climate change etc, China is basically a huge workshop without safeguards for the workers/environment and so on), but also undemocratic. Whichever country is in charge is going to breed resentment and distrust, and at the moment there isn't a single country on the planet whose politicians are trustworthy anyway.

So it won't work, will never happen and would lead to some pretty ugly scenes. Truth is, unregulated capitalism is failing, draining the public purse as it accuses other political ideologies of doing, all the while managing to should the poor with the burden of austerity whilst the rich see taxes dropping. I've said for years, capitalism is incapable of meaningful self regulation and acting with social responsibility because the people who are most involved with it are greedy tossers and can't help themselves.