Lots of products, including ours, running on Go. It's not a fad, it's a useful tool. Not the best programming language in the world, but still allows you to produce great results in a short time. Kind of like Delphi what used to be for the Windows desktop.
Is Java a fad? Its early years were much more hype driven than Go has been at any time during the 10 years Go has been around.
Python? JavaScript? Ruby? Rust?
What I like about the Go community is that it appears to be very measured. Unlike many other communities where the way a language is used becomes bigger than the language. Like Spring and Java. Rails and Ruby.
Or Rust and “look I reimplement X despite nobody giving two shits”. :-)
(My big disappointment with Rust is that it hasn’t found its niche. I’d like that niche to be embedded operating systems. We could certainly use Rust there, because C, C++ and the utterly shit Python-junk used to stich things together is just painful . Competing for attention in server development or any other area that has very strong contenders is clearly an uphill battle)
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.