Add cluster nodes dynamically to cluster hosts

Current situation: when creating a cluster host, the nodes have to be added manually (i.e. Setup -> Hosts -> Create cluster -> add nodes)
feature wish: according to Checkmk motto "everything is a rule" ditch the above and let users create a rule that adds nodes automatically to clusters via regex, labels ....
Advantage: newly (dynamically) added hosts are then automatically added to a cluster according to rule conditions.
A node host removal somehow already works (via service discovery on the cluster when a host is (automatically, via DCD ...) removed.
To avoid empty cluster hosts, the "datasource failing" feature (i.e. Check_MK goes "host configuration requires a datasource but none configured") could be extended to "cluster host configuration requires nodes but none configured"