With the announcement that Adelaide’s Carols By Candlelight has been cancelled, you’d have to imagine that Carols in the Domain in virus-riddled Sydney (well, the situation is currently worse here than in SA…) is likely to be cancelled for 2020?
If by some miracle the event does go ahead, I’d probably expect it to be in a considerably reduced form! Although knowing how the format of CITD hasn’t really evolved much in decades (different sponsors and Channel Seven personalities as hosts, but that’s about it really! 
), I reckon they could get away with replaying an old telecast or doing a “Best of” special.