It's as FOSS as the VirtualBox open source edition.
> Do you expect Oracle to merge this?
That would be nice, but I wouldn't hold my breath. Oracle gonna Oracle.
> If oracle doesn’t merge this, will you keep on maintaining it, potentially forking VirtualBox?
We don't intend to fork VirtualBox. VBox has a somewhat modular architecture where you can plug-in different hypervisor backends. That's what we did. It's not as modular, but our changes to core VirtualBox code is very small.
As far as our plans go, we are pretty open at this point. We are very interested to get to know people that find this useful!