"Vintage" as applied to sewing machines has a somewhat specific meaning. Antique sewing machines are ones made before 1900. Vintage machines were made between 1900 and about 1970. Modern machines are anything after about 1980.
Vintage machines were made after all the early wrinkles were worked out and before the manufacturers switched from all metal construction to using plastic in the housings and mechanisms.
The all metal machines are nearly indestructable. About all that can kill a vintage sewing machine is rust or being dropped on a hard floor - cast iron tends to be brittle.
Supplies (needles, bobbin cases, replacement parts, etc.) are often still available for popular vintage machines. Sometimes because there's a lot of new-old-stock still around, sometimes because modern machines still use parts originally designed for older machines, and sometimes because there's enough of a market that somebody, somewhere, fired up a production line to make new parts for the old machines.