I don't see the Amero happening. First of all, what good does it do the US gubbermint to let Mexico and Canada in on the reserve currency game? If it was the only thing that could save us as the reserve currency I can see them trying, but do you really think the rest of the world is gonna be impressed by a US currency strengthened by Canada and Mexico?
I don't. They'll go running to the Euro or the Yen.
Read the history of the European union and the enactment of the Euro.
You might change your opinion.