It's important to understand that, by virtue of having been bestowed with a monopoly over the web, JavaScript holds a great deal of leverage as a language. If you want to develop for the web, you pretty much have to adopt JavaScript into your stack. It's no surprise, then, that Node became so popular. Being able to use that language you're forced to use for the client on the server and to run the same code has major benefits. The Node and npm developers got many things right to be sure. But Node and its ecosystem, by virtue of offering JavaScript, benefitted immensely from developers' desire to unify a previously disjoint part of their stack.
I find myself asking instead, how far will JavaScript's reach continue to stretch? Electron and React Native have become extremely popular. It's not just speculation, there is undeniable momentum.