Welcome to Qantas, have a nice day (lol) <tongue in cheek>
This has been the trend in the recent CoVID years... It is understandable that there are a lot of pax worried about their plans and calling up the airline and hence the queue is getting longer & longer ... It helps a bit if one has got Platinum or more with QF, then the waiting times are little shorter
It has been my experience that I get through quickly if I called early in the morning or late at night ... I remember once I called at 11 PM and got connected fairly quickly. But do note that you might not get AU based staff, probably South Africa or Philippines based CC. IME, I have been calling up QF fairly regularly for domestic travel needs/changes etc, and on average, my waiting time has been 15 mins or so ... There was one instance where it took me over 30 mins, but it was just that one instance ...
As mentioned by
@jpp42 , pax will be moved to different flights in the case of a cancellation. The pax will also be given the choice to accept/reject the choice offered. You may also be able to call up the airline (which, we have already established, isn't as easy as it sounds) and ask for a different option. You may also choose to fly out of a different city in India (say, BOM, BLR, HYD or MAA) which are well connected with DEL domestically.
I can understand how frustrating & helpless one might feel when stuck overseas during a pandemic, with the airline playing the cancellation game. I had a mate who was going to be on the QF67 and is still here in AU due to cancellations. I guess, in this instance, the name of the game is "waiting" and unfortunately, it's not a nice game ...
btw, Welcome to AFF
Glad to have you here