First off, I got the terms wrong, the bills will no longer be legal tender, which means there is no legal obligation to take it in. The banks will still exchange it at face value. This brings up an interesting loophole when it comes to collecting. Even though there's 750k of $1000's out in circulation, I'll bet only a small number of them are with collectors ($1000's are mainly used for easy laundering), so demand will exceed supply when it comes to collectors. This would no doubt bring in counterfeiters to balance the supply, which for non currency experts, pretty easy to fool. You can't really validate it so it's an easy scam. Not only that, because it's no longer legal tender, it's not classified as counterfeiting under Canadian laws.
http://laws-lois.justice.gc.ca/eng/a...6/page-93.html
448a defines counterfeit money as:
Since it's no longer current, this law no longer applies. There's a case for fraud depending on how it's advertised for sale, but the punishment is a slap on the wrist compared to counterfeiting money.