Hi Bertl, we've had this discussion many times - particularly in the early days of WKC. It's always a spirited conversation! Not sure we ever settled on a definition, and not sure it matters. For me, the "Modern" era began with the One Touch system of ash management - arguably the biggest leap forward since 1952. What year was that? That would make any kettle prior to that "Vintage". When Weber introduces the "No-Touch" system, I suppose even today's kettles could become vintage.
There you go - my two cents have been spent.