rqlite (and Raft) doesn't assume this. All it states is that for the cluster to make progress i.e. apply a change in a consistent manner, at least a quorum of nodes must be online and in contact with the Leader (which is one of the online nodes). Every node in a rqlite cluster knows what size the cluster is and therefore requires that (N/2)+1 nodes acknowledge the change before that change is committed. The Leader node performs this coordination.
The scenario you outlined above is obviously possible. But in that event the cluster is down -- the Leader (let's say it's node A) cannot contact a quorum of nodes. No changes can be made to it.
rqlite (and Raft) doesn't assume this. All it states is that for the cluster to make progress i.e. apply a change in a consistent manner, at least a quorum of nodes must be online and in contact with the Leader (which is one of the online nodes). Every node in a rqlite cluster knows what size the cluster is and therefore requires that (N/2)+1 nodes acknowledge the change before that change is committed. The Leader node performs this coordination.
The scenario you outlined above is obviously possible. But in that event the cluster is down -- the Leader (let's say it's node A) cannot contact a quorum of nodes. No changes can be made to it.