That's exactly how it rolled out when the EU went to the Euro, for example. You had a limited time to turn in your French Francs, Italian Liras, etc. for Euros. After that: congratulations, you have a coin collection.

Can confirm. This is exactly how it went down in Latvia a little over a decade ago when we switched. I think the grace period for using the former LAT was appx two yrs, and even after full transition you could still use LATs in a few places e.g. microbus transit, vending and some kiosks, etc. But now, a dozen odd yrs later, the old currency is only good for one thing: the finest outhouse wallpaper you can imagine!