Realistically, when the government sends in the army over a few cases of COVID - 19 in Victoria, international flying is unlikely to resume this year with the exception of NZ and possibly limited travel bubbles. Profitable international flying will take even longer to come back and the network planners will be starting from scratch with a clean sheet of paper rather than simply reinstating the previous routes. Due to the distances involved in international flying from Australia, widebody aircraft are normally required to reach most destinations in Asia and beyond, these will be difficult to fill at first. Running a hub through Darwin with the B737s into SE Asia could be considered until direct routes become viable again.
City pairs which previously supported direct flights may have to go through a hub instead, double daily may go daily, wide body may go narrow body. Certain routes may turn into cash cows if competing airlines withdraw. Matching capacity growth to pax growth needs to be done right else money is lost or profits are missed.
When to jump back in requires careful judgement due to the lead time required and the necessity to operate at a loss for as short a period as possible. SIA are flying a skeleton international network due to the need to maintain connectivity, but this needs Singapore government backing as pax numbers reaching three digits is cause for celebration.