Good point, because one has to ask, why now?
I don't want to come off like a Ron Paul or Dennis Kucinich nutbag, but maybe their idea (the big three) planned this economy collapse we are in right now. The "new" Amero, along with the merged economies (Canada/US and Mexico) will be touted as the only way to stabilize the individual countries economy this way (i.e. the EU).
The Amero may have to be a 3 sided coin to appease all 3 countries with their slogans and images.
Disclaimer: most of this was meant to get a laugh, but taken with it a grain of sea salt.