For my own education: Python with a good standard packaging system and solid, standard async capabilities would be solidly going after the same areas Node.js has done so well in? If not, why not?
Personally I'm not convinced that the Node.js callback hell is a good way to get high IO performance. The Golang way of doing it with normal, blocking libraries and Goroutine's seems ideal as it doesn't burden the programmer as much.
In 0.12, node will ship with a version of v8 which has generators (hidden under the --harmony flag), which are shallow coroutines, which allow for the same code style as go-routines.
Existing non-blocking libraries will be reusable with generators via e.g. https://github.com/jmar777/suspend or https://github.com/visionmedia/co etc.
Performance could also potentially improve as in V8 closures are much more expensive than generators.