Hi all,
I've just created the missing plugin to revert V-Ray materials back to internal.
For now it's target is only to prepare file export via .fbx and similar, since this operation didn't support plugin material.

here link to description:
C4DToVray

and here direct link to Gumroad:
https://gum.co/pgZTY
it has a reasonable price of 10$ (or more ;-)

Any suggestion will be really appreciated.