The promise of reciprocity from the United States in the agreement is to pursue equivalent levels of information exchange. It doesn't mean identical, and since we don't tax on the basis of citizenship, we wouldn't be interested in getting information on non-resident and Canadian citizens.
What it could well mean is increased due diligence requirements at U.S. financial institutions to identify Canadian residents who hold accounts there. It could also expand the reporting requirements to equivalent types of information that, under the agreement, Canadian financial institutions are supposed to report. An example of that would be account balances.