I am about to start the process of moving the WildFly Elytron Subsystem
into WildFly Core.
https://issues.jboss.org/browse/WFCORE-2352
For now I would suggest if you are working on changes to continue to
submit PRs against the subsystem directly but be prepared that any that
miss the cut off may need resubmitting against WildFly Core.
Resubmission should not be a big task as the structure of the subsystem
project should be largely unchanged.
Regards,
Darran Lofthouse.