Hi all! I wanted to provide some quick context on how hubs that may not be online function with the Hub Replace feature to hopefully answer some questions here.
Hubs with software supporting the Hub Replace feature periodically create encrypted backups of information like network keys for its supported mesh networks, driver state, and other key pieces of information. So if a replacement is requested and the “source” hub is offline the most recent backup available will be used for the replace operation. If the hub is online a fresh backup will be created and used. Replacing an offline hub is “best effort” and may miss some changes that occurred between the most recent backup and when the hub went offline, so we recommend performing a replace when the source hub is still online if possible.
It should also be noted that if you delete the hub from the SmartThings platform the backups will be removed for privacy reasons. So you should leave the hub you are looking to replace on your account (even if it’s in an offline state) until you can perform the replace.