TL;DR: The world is likely to soon be an archipelago of coronavirus-free islands in a sea of infection, and will remain so until an effective vaccine or treatment is globally available.

First up, a disclaimer: I’m not recommending any particular course of action, since I don’t claim to have the expertise to do so.  This is based entirely on analysis of the second-order effects of actions already being taken around the world today.

Creating islands

China has demonstrated to the world a simple and brutal but seemingly effective strategy to suppress the coronavirus pandemic. Isolate people in small groups, wait out the incubation period while removing the sick, repeat until everybody is healthy or dead.

Once you have created a coronavirus-free space, you also need to regulate entry to it to ensure no new carriers slip in.   Basically the same approach applies here as well: create an “airlock” by strict quarantine of all would-be entrants for 14 days, after which the healthy can enter.

Stating this in a few sentences is easy.  Actually implementing it with no gaps, meaning every local transmission and every infected visitor is successfully caught and quarantined, is fiendishly difficult, and many will try but fail.  If so, the world can soon be split in two:

1. Islands, where local transmission of coronavirus is not present and there are strict entry controls to keep it that way.
2. The rest of the world, or the sea, where coronavirus either is spreading locally or can be reintroduced at any time due to lack of effective controls on population movement internally or externally.

It’s important to note that islands need not be entire countries. A reverse quarantine zone, intended to keep disease out, can be implemented by any polity with control over its territory and the ability to keep out outsiders, be it a state, a province, a city, a farming village or a mountain cabin full of preppers.

So what?

If this pans out, the implications for the next year or two are enormous and complex, but we can draw a few straightforward conclusions:

• Travel will remain extremely restricted.  Islands, paranoid about becoming infected, will be slow and cautious about opening up to other islands, hostile to anybody entering from the sea, and unwilling to send anybody into the sea themselves.  Would-be islands, trying to prevent new carriers from entering, will also restrict travel and apply quarantine measures.  Truly dysfunctional governments will be unable to restrict travel in or out, but their population will have other priorities.
• Poor countries are likelier to end up under water.  If they lack the ability to enforce population isolation, keep their borders locked down, detect the inevitable slip-ups and track down their contacts fast, they will not be able to stop transmission.  Premature declarations of victory, followed by lapses back into the sea of community transmission, are likely.
• Larger nation states may fragment.  If a country-level island is not possible, smaller entities may try to form their own.  For example, the Australian island state of Tasmania has already requiring all arrivals even from the rest of Australia to quarantine for 14 days.
• Herd immunity in the sea will not end travel restrictions.  The population of the islands is not immune, so they will continue to heavily restrict travel from the outside.
• Only universal vaccination or an effective early-stage cure will dry up the sea.  These are the only controlled ways to either bring immunity to the islands, or make the risk of getting sick tolerable. Even after islands vaccinate their own, they will continue to restrict travel from infected zones, because no vaccine is perfect or available to all.