Really only workable using the cloud backup with the radio data. I had this set up for a bit in a test mode [BETA] Hub Failover - AKA an opportunity to protect or destroy your environment and it did failover reasonably well, but like Bruce pointed out the zigbee devices are the kicker. LAN integrations can also be problematic depending how they're implemented, but if you're primarily a ZWave installation this might get you there.
It also takes some regular care and feeding, so not completely set and forget.
