It hasn't solidified for the same reason that C++ in many ways still hasn't solidified. Software is a very young industry by many standards and we still haven't found the best way to make it. Rust is one way to do it, but there are many others besides, in the end which tool wins out is less important than that we make some progress and get out of the tar-pit that we've been stuck in for the last two decades.

All we seem to be doing is make more layers of gray goo and leaky abstractions that we then plumb together to attempt to make reliable systems. It still doesn't feel right to me.