Yes, this is nothing new, there are a few meta-circular JVMs, just they weren't commercial products.

Jalapeño from IBM,

http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.25.8...

Sun's own Squawk VM, used on Sun SPOT before IoT was a thing.

https://www.researchgate.net/publication/221320697_The_squaw...

https://en.wikipedia.org/wiki/Sun_SPOT

Regarding Project Metropolis specifically, you can find the information here.

"Your next JVM: Panama, Valhalla, Metropolis by John Rose"

https://www.youtube.com/watch?v=OMk5KoUIOy4

http://cr.openjdk.java.net/~jrose/metropolis/Metropolis-Prop...

Note that I wasn't completely fair, the .NET team also has some plans to incrementally move the runtime into C#, but so far it has only been mentioned on an InfoQ interview, no official plans revealed.

https://www.infoq.com/articles/virtual-panel-dotnet-future

"So, in my view, the primary trend is moving our existing C++ codebase to C#. It makes us so much more efficient and enables a broader set of .NET developers to reason about the base platform more easily and also contribute."