Go is over a decade old, not counting a couple of years of development in private. I'm not the biggest fan of the language but it's hard to think of it as a fad.
Fad or not, in terms of programming languages, ten years isn't such a long time. It typically takes a few years just to reach the eco system maturity and community size needed to become a popular language. Rust is also ca. ten years old and I'd argue that it still haven't reached its full potential.
The language absolutely was a fad for a while. The shiny new thing everyone was moving to. That is how languages get popular. But languages unlike terminology don't just disappear.
