WildFly is currently able to externalize @Stateful EJBs to a remote Infinispan-server cluster by use of an invalidation cache and a hotrod-store. This however requires clustering on the WF side, and is generally less efficient than a session manager that uses hotrod directly. Additionally, such an implementation will generally have simpler affinity requirements, using strict affinity to some namespace, and no weak affinity.
This requires:

• A new hotrod-passivation-store resource in the EJB subsystem
• A new wildfly-clustering-ejb-hotrod implementation of the EJB cache SPI