Unlike the penny which may cease to be minted the US $1 banknote will not be stopped. One dollar coins have been rejected by the US public starting with Eisenhower Dollar (too big, too heavy) then the Susan B. Anthony Dollar (too easily confused with the quarter) then the Sacagawea Dollar (just because and we don't want to carry it around), the Presidential Dollars (same reason). Unless you're using one as a token in the subway or vending machine there's almost no circulation. Hand one to a human to but something and they look at it and look at you with a “what the heck is this” expression.