I think they're being reimplemented in Kubernetes. Kubernetes provides scale-ability, fault tolerance, and the pieces you need to build robust distributed systems. There's no need for this from the language itself. It's actually disadvantageous to mix Erlang and Kubernetes, because Erlang really wants a stable set of node names.

It's not a good fit for the way in which we're doing fault tolerance in the cloud. Erlang focuses on not crashing the BEAM, by letting processes crash while allowing graceful degradation of service. Supervisors are akin to Kubernetes deployments. Processes are pods. The pods themselves should be designed to crash gracefully.