This is part of an overall effort to eliminate non-optional dependencies on the org.jboss.as.remoting module. Both because depending on extension modules has a code smell but specifically because the org.jboss.as.remoting module brings in fairly large dependency tree.
The ejb3 subsystem has two general categories of use of the org.jboss.as.remoting module:
1) A number of child resources use it. The ResourceDefinition for those can use registerAdditionalRuntimePackages to record a hard dependency allowing the module.xml to make it optional.
2) AbstractOutboundConnectionService is used by deployment code not limited to particular child resource. But once
WFCORE-4955 is done and integrated this can be replaced with use of the new interface from the org.jboss.as.network module with injection done using the capability.