Mr. Joseph Yam, former chief executive of the Hong Kong Monetary Authority, has proposed a package of policy changes that, if implemented, would undermine and destabilize the Hong Kong dollar—a unit that has been rock solid ever since Hong Kong established its currency board in 1983.  And if you doubt that dire conclusion, reflect on the fact that Argentina blew up its famed convertibility system (OK—it wasn’t a currency board, but only an unusual pegged setup) in 2001 by adopting a series of Yam-like measures.