Over a 5000 year timeline I would hope that we would not lose the technology to carbon date artifacts. Maybe we lose all the context so that archaeologists can't know whether coca-cola or modelo were places, people, gods, or products. I'm willing to bet, if past performance is any indicator, that they would be identified as items related to cultural deities worshiped by those who consumed their deliciousness in rituals lost to time. Maybe even seasonal fertility rituals. Archaeologists have a tradition of just making shit up as they go and figuring it out once they have enough real data to lay all the speculation aside.