I always get a new list of requirements from my immigration office. Every year some things change.
On the list I get, they also mention the letter from the bank in Thai. That is easy to show to people working at the bank. Without it I would never be able to explain what I need, because they always look a bit puzzled when I show them.
" ... banned until further notice." does not sound good. I hope for the foreigners with Non O stuck abroad with Thai families they will be able to come back together with Thai people stuck abroad. But people on a tourist visa seem to be screwed, last in line.
Not flying is happening right now, but I do not see people accepting it for a few years.
Many people accepted restrictions as they thought it would be for a few months. But all over the world you can see people getting tired of restrictions after only a few months.
The world already proved they can not contain this.
I do not think it is possible to turn back the clock 100 years and people not being able to fly all over the world. If there are new strains of this disease, it is no longer short term pain but will take many years. If ever they can find a cure, or we will just have to live with it like the flu.
I do not expect immigration policies to be very favourable for the UK. I read many times that if they open up borders, they do not want to open up to high risk countries.
But that is just my thought, just waiting until the next anouncement about international flights is the only thing you can do now.