Well, no. The only way the contents of a beverage can could totally leak out is if the can were punctured or corroded through. That or a manufacturing defect that kept it from being completely sealed, which is a rare occurence. Barring corrosion, a modern can could hold its contents indefinitely, but in practice, corrosion would eventually eat throgh the container, spilling the contents. I have no figures on how long this would take for cans made today, but I suspect at least hundreds of years.