After changing the root password, the host will not immediately disconnect from the vCenter server. However, if the host gets disconnected from the VC in future for some reason, it will not connect back to VC automatically unless you give the new password. I would suggest not to get into that situation in future unexpectedly , since the hosts are in cluster, try to evacuate VMs using vmotion and change password, reconnect the host with new password . do this for all the hosts, you may avoid issues in future.