- js / node.js is very young, it might fade out of fashion, and in 10 years it is not impossible that good coders in js will be hard to find.
- Readability and simplicity are prominent in this context, and js has a syntax that is less than optimal in this regard.
- Maintenance tooling may be lacking.
If I were to choose a language for a project that I new will be big and will need care in 10 or 20 years, I'd hesitate, and maybe choose Java (which I hate) or Python (which I hate less). If in a risk-things mood, I'd give Go a try.