Even when flights resume, if social-distancing is still be practiced (which is highly likely), the practicalities of handling passengers will be immensely difficult. Two metres separation between people at bag drops/check-in, security and the gate will make scheduling of flights radically different from what we are used to. Boarding the aircraft even with a significantly lower number of passengers to maintain social separation will need to be well-controlled, needing extra staff and time.
The capacity of all flights will also need to be drastically reduced. For example on a typical A320/737 only seats A and F could be used to ensure some distance is maintained from cabin crew, and only every third or fourth row at that, reducing the capacity on each flight to around 30 or so passengers. It would also not be possible to provide any inflight sales, so the pricing structure of flights will need to reflect this - I think we could easily be looking at fares pro-rata similar to business class in the 1980s, with typical 1.5 to 2 hour European sectors needing to be around £500.00 GBp each way.