I've never heard of them cancelling a program before it was scheduled to end already. For example the STV (Special Tourist Visa) that was issued during covid, that allowed a 90 day stay, and could be extended 2 times for a maximum of 9 months in Thailand. It was a temporary program, and after the program ended some immigration offices also stopped allowing people who already had the visa to get additional extensions.
Is it possible for them to end it? Of course, they gave it and they can do whatever they want.
The most likely thing if they ended it would be that they still allow the people who have it to continue until theirs expires.
The worst case scenario would be that they immediately cancel all DTVs and anyone with one can no longer enter Thailand with it.
The middle ground would be that they cancel the program so no one can get a new one, and then severely restrict the people that already have it by requiring them to show proof of an ongoing class/medical treatment, or proof of remote work and their bank account each time they enter Thailand until the visa ends (slightly similar to how anyone with an OA visa must show their required health insurance each time they enter Thailand with the visa).
they just want to see the equivalent in baht from your bank account anywhere. Not sure how they calculate the exchange rate. I believe most of the embassy websites just state for the requirements to show xxxx in the local currency so there's no needing to figure out exchange rates at all.
best to go to the immigration office and ask them for their handout of requirements for the 1-year extension. That way your can be sure you got everything and get it done in one trip.
he wouldn't be able to do it online anyways. The first one must be done in person. But he isn't required to do it at all because he's not on the extension yet