I saw that, and I wouldn't call Gertrude or some of the others they mentioned, like Ethel, "traditional" names as such. There is a world of difference to me between Gertrude, and names like Mary or Katherine. Gertrude was not used in England before around the 19th century; it's a German name. It became trendy as part of a larger vogue for Germanic sounding names, before that trend died out in the early 20th century. Likewise, a lot of Old English names were revived from obscurity in Victorian times, before becoming unfashionable. A name like Ethel spent hundreds of years in name purgatory before it came back into fashion. And now it's been out of fashion for a hundred years - well, relatively speaking, that's not long. It's almost like an article appearing in 2108 bemoaning the disappearance of "classics" like Chelsea and Paige.
On the bright side, if you look at the British charts, they are predominantly traditional. Almost overwhelmingly so at the top end of the chart. Looking at the top 50, apart from a few nicknames as given names like Katie and Evie, there are only Madison and Summer which strike me as modern innovations. The boys' list paints a similar picture. Yes, there are 'trendy' new names, just like there have been in any era. But to say that the use of traditional names is "in freefall" when the boys' top 10 names could almost have come from 100 or 200 years ago strikes me as silly. I'm actually quite proud of our UK name charts and think that as a country, we tend to do names pretty well :)
(By the way, Lethe, I'm not criticising you, just the article! Thanks for posting it!)