"You can't make an antique. And nobody can write a folk song."
Of course you can make an antique, but at the point at which you make it it is merely furniture, pottery etc. It becomes an antique with time. (traditionally a hundred years)
It will only become a valuable antique if it is inherently well made at the time of construction, or if it acquires status in some other way, perhaps by rarity, or by the high status of its creator, or by historical associations picked up over time. Many of these may have no intrinsic value- A Churchill Cigar butt for example.
Some modern things fall into these category and can be considered "Classics" or antiques of the future.

Similarly with songs.

Somebody wrote them.
Some, old or new, are inherently good songs.
Some are rare and unusual (not necessarily good though).
Some are written by people who are respected for their songwriting ability.
Some are run-of-the-mill potboilers, but have memorable historical associations.
Some modern songs fall into these categories and can be considered "Classics" or folk songs of the future.
Cheers
Dave