Considering that this would be a group of people with enough money to pack up and move to a different country on a whim -- and that Canadian currency is basically Monopoly money right now -- it would really only take one or two bidding wars between Hollywood exiles over a 20sqft dumpster in West Van (market price: $1,287,395.27) to finally burst this country's real estate bubble.
Alternatively, for those who prefer adventurous living and soul-killing desolation, there's always scenic Newfoundland.
Unlike the freedom-loving people to the south, it is generally frowned upon in Canada to carry assault rifles around at, say, Toys “R” Us. We can only hope that the influx of new arrivals would be able to quickly master the preferred Canadian methods of defending one’s honour: devastating passive-aggressive barbs masked as politeness, and/or trash-talking one another during an inebriated bonspiel.
The most obvious perk of surrendering American citizenship to the Mounties at the border crossing is publicly funded healthcare. Admittedly, seeing a doctor, or getting surgery or radiation therapy, without having to worry about going bankrupt is pretty damn great -- although God help you if you need to buy medication or go to the dentist.