According to Miriam Webster, Noun, a work of art, piece of furniture, or decorative object made at an earlier period and according to various customs laws at least 100 years ago. A doctor I knew had, over many years, filled his home with antiques. He explained that he liked having furniture that grew in value as it got older. Nothing refinished, which reduces value. It felt like living in a museum. I think your piece is a classic design. To become an antique in the future it would likely need to have a back made of glued up, half inch lumber. Preferably using hide, or brown glue. Nice to see when old projects are prized.