I'm not really sure how this would work (ignoring that Trump would never let it happen). Do all the people living there get citizenship? I'd imagine a flood of people trying to move there just to win Canadian citizenship if it was announced ahead of time, so the only thing I can think is that it'd be anyone who's lived there for a certain length of time or up until the announcement date. But then, do family members get citizenship as well? Like what if the child of a family there is off at college when it goes through. It'd be unfair to split up the family so the children would need citizenship as well.
Maybe I'm overthinking it though considering its such a tiny underpopulated area