Thanks to Milan Bartos, there now is imkmsg, which supports structured kernel logging. This module will become available as part of rsyslog 7.1.5 later this week. The module was created with the help of Red Hat as part of the lumberjack effort for a better and structured logging infrastructure.
Note that the rsyslog v7 engine supports numerous enhancements for simple processing of lumberjack strucutred logs. So imkmsg is a natural fit for that version. As Milan told me, there is still room for improvement inside the module and some nits may exist and be fixed within the next weeks. However, we would appreciate feedback from early adoptors.