Some times simply communicating that they have nothing to communicate (at this stage) is important.
If the announcement is not a boarding call or boarding time, then IMO the end of the announcement should also advise when the next PA update should be expected by customers.
In regards to the OP's situation, I don't think that VA controls allocation at its gates at SYD T2, which means that often VA don't know where a delayed aircraft will dock, sometimes until it docks (with aerobridge staff forced to do a last minute sprint to the gate to drive it). I have also seen gate changes at the last minute, just prior to boarding, where operations have obviously commandeered an aircraft at a different gate, and changed its destination (confusing two sets of passenger groups in the process).
IME Qantas' ground staff are excellent at keeping passengers informed in these situations, and Virgin's are extremely poor. (But these gate problems seem to arise significantly more often at VA in SYD, than at QF in SYD!)
Many people become anxious when flying, and sitting at a terminal with a boarding pass that shows departure time in the past, can worry to the best traveller, especially without staff reassurance that they haven't missed their flight.