Are penny hoarders wasting their time?

I have heard some people cobble as many pennies together they can, to lay hands especially old pennies (the ones that were made of copper). They have the idea that one day the penny will be retired by the government and they can take the pennies into a scrap yard or some other places that takes metal and get the value of the weight of the copper which would be more than the penny was worth as money. If I know the US government, if they ever retired the penny they will recall all of the pennies than leave millions out there to be melted down for money. If the government seeks to reclaim the pennies so it can redeem the value of the copper, would that leave all those penny hoarders efforts in vain?