Andreas did not like the Rust community. It sounds like that is still true.
He also thought that Rust integrates poorly into project with a deep C++ OOP hierarchy. That is probably still true as well.
It is telling that the first project was a total rewrite of the entire JavaScript engine. There is no shared hierarchy and a well defined boundary between the C++ and Rust code. That may be a sign of things to come.
We may see entire modules that are either all Rust or all C++ rather than more fine grained mixing.