Just as one precision, 2.1 million cards are classified as dormant, but they can be used. They have not been deactivated. A flag will go up when they're used, but not all departments are treating those warnings consistently.
As for the question on the potential misuse, we can't estimate that, and I don't believe the department has estimated that. It has to be recognized that for any of the programs where the social insurance number is used, other documents also have to be provided. It's not simply the social insurance number that would give someone a right to benefits.