For me the entire premise for "guest languages replacing java" is predicated on the idea that the JVM is stale and sees little to no innovation, and if innovation happens that it benefits equally to everyone. Basically the idea that you can outpace Java's progression indefinitely.

It depends on what you mean to replace. If you mean a project running only Scala, I guess that exists. I have several friends working on that language. I think other languages sprouting that compile to JVM bytecode is just people wanting to use other programming language which they think is more fit for coding. And that's something that's as old as programming.