Aviation will quickly over the coming years move to where trains and shipping have dwindled to, the pandemic will give airlines the helping hand to move things faster in that direction.
Air transport WILL NOT dwindle, quite the opposite. The masses have tasted cheap international travel and they liked it, if air transport dwindles how will they travel?
It wasn't that long ago in the scheme of things that we had trains with segregated seating, 1st/2nd/3rd class coaches, ships and ferries the same, now its all one ticket on the cheapest possible platform.
Spoken by someone living in the bubble that is Australia. Try looking at Europe or India or Japan.
https://www.eurail.com/en/help/inter...-and-2nd-class
https://www.japan-guide.com/e/e2016.html
https://www.amtrak.com/guide-to-fares