Once a pair of countries have achieved an adequate level of vaccination of their populations, they will be able to open up to each other. A vaccinated traveller with a negative COVID test is unlikely to spread the virus on arrival in a country with a +70% vaccination rate. The odds of him catching the virus after his jab, testing negative and then managing to infect someone else who has also been vaccinated and having them go onto get seriously ill or die must be minute. Some countries may even be desperate enough to allow vaccinated arrivals before their own population has received the jab, Thailand is looking at a partial opening in September as the consequences of second washed out tourist season are dire.
The Israeli data showing a 0.04% infection rate after the second dose and a 0.002 hospitalisation rate is very encouraging.
https://www.theguardian.com/world/20...-exit-pandemic
The risk level would be acceptable to allow a gradual, regulated and monitored opening up of borders. We won't get 100% elimination of COVID, it's something we will have to live with. Annual jabs, increased hygiene standards, testing and social distancing will be the new normal for the foreseeable future. Online verification of vaccination status wouldn't be difficult with governments maintaining a database and allowing airlines access to it.
Unfortunately for hub airlines, the new travel arrangements will favour point to point flights and smaller aircraft. Mixing of travellers during enroute connections will be avoided and the numbers involved won't be filling the new generation of VLAs anytime soon. A B787 from Europe direct to Bangkok will be happening well before a connecting flight using A380s via the Middle East is a realistic proposition.
AIDS has been with us for the last 40 years and was a virtual death sentence back in the 1980s but we learned to live with the problem, every country has 1000s of people infected but travellers aren't generally tested unless permanent migration is involved.