My manual said to inspect the anode rod after the first year of use. If little deterioration was present inspection could happen at three year intervals. I’ve never inspected a rod on any hot water heater I have ever lived with. I hope regular inspections and rod replacement can keep mine running for quite some time. Is 20 years reasonable..... I’m not sure it is.
Every water heater I have replaced was due to tank failure. With the hybrid, I suspect that will continue. If the heat pump fails, it will most likely be a PCA failure. It seems most OEM appliance manufacturers don't know how to design a reliable PCA.