The market for travel is built on the need or desire to physically meet people - vfr traffic and business meetings. Both of these things are effectively off limits. Then there is tourism but with almost all hotels shut, where would folks stay?
When restrictions on the drivers and enablers of travel start to be lifted there will be more flying. The immediate question for airlines starting passenger flying programs again is 'where will they be allowed to fly to?'. Who would want a plane-load of Brits or Belgians or Germans etc etc?
This crisis will create a deep seated xenophobia in places that we used to travel to with ease; as well as our own home-grown version (frankly who would welcome a coach load of chinese tourists turning up at their venue right now or even in the medium-term given that they started the whole thing). That will take some time to dissipate. Brits literally may not be allowed in to some countries for months to come or longer. It will be a long slog back to what was there before (3-5 years imo). Even when a vaccine is readily available, many countries may insist on a certificate of proof prior to entry. The barriers to travel are not coming down any time soon even if the desire returns.