Yes, that looks about right (except discovery.zen.hosts_provider -> discovery.seed_providers).
Note that you wouldn't set cluster.initial_master_nodes at all on any other nodes in this case.
You might also like to call this API before shutting the election node down:
POST /_cluster/voting_config_exclusions/election_node
and then this after it's gone:
DELETE /_cluster/voting_config_exclusions
That'll make sure that the cluster is ready to lose this node before it goes away. Otherwise there's a risk that you shut it down too soon leaving the other nodes without a master.