Nairobi, Feb. 3 -- It starts to become clear now, as we watch the latest round of border closures, that international travel may never go back, in our lifetimes, to where it was before Covid-19.

For sure, earlier this week, it fell to me to find flights for someone from the UK to Slovakia. The flights are still allowed. Yet my flight search engines, normally filled with hundreds of options in a ladder of pricing, returned a bunch of messages all the same, apologising for being unable to find any combination of flights at all between the two destinations, or from Austria, or to bigger UK airports.

I presumed the engine must have stopped working and tried others. But the problem was the flights.

For travelling now - as a client of mine rel...