What will happen to our old fiat coins?

As we all know that in every nation in this world had its own money bill or currency. There is a bill currency and cents which represents by coins. Now a days mostly coins is being put aside because of its low value. They dont think of the importance of this coins. The whole value of the money will not be completed without cents. The supermarket also needed those coins for changed. In some cases, a very rare and century aged coins are now valuable. Some coin collectors are buying those old coins and in exchange for a more value of cost. Still, we can use our save coins .so dont dump or keep in any where else. Time will come ,those coins can be more costly compare now a days.