Solar events as well as nuclear can cause an EMF pulse that destroys all transistors, thus inherently all DAB radios.
As well as the vast majority of FM receiver which are also nothing but transistors on a circuit board.
I had read about Denmark switch to full Dab.
France is on the same path, it's expected to be official somewhere around 2033 but I doubt they will manage to meet that deadline as Dab seems to only be a viable option in the larger cities for the moment.
do we compromise the option of broadcasting to survivalists who have tubes receivers?
I don't think they're a large population to be considered worth the investment but I may be wrong, obviously.
As for the postal service... Here in France, La Poste, our public postal service is not doing that well either. Prices keep increasing almost every single year, which doesn't help either. They have not yet started talking about getting rid of the service itself but I would not be surprised if they were to begin discussing it sooner than later, as they already are actively discussing the 'optimization' (aka the killing) of our various public broadcast stations (TV and radio).
The real issue, imho, being that less and less of us are willing to use snail mail. And good luck getting younger people interested in trying it. I mean, no likes/comments, no immediacy and the obligation to use pen and paper,... Not the most trendy things, I'm afraid. Not even mentioning how much waiting and patience play a key role in enjoying sending and receiving snail mail from your friends abroad.
Post-Internet, radio has surely lost listenership
It sure has. That being said, I was a pre-Internet listener and to this day I'm still actively listening to my favorite radio stations, just less. And so does my spouse.
I spend less time listening to the radio because of... my iPad that I use as a podcast receiver and, now, as a an Internet radio receiver too.
I don't use Dab, even though I very recently considered starting doing so but had to let go of the idea as I was not able to find a decent Dab radio set. One that would have enough favorite buttons, dedicated buttons I mean not menus (I use 6 on my small portable FM radio that has 10 available total, and I would like to get at least as many on a much more modern and supposedly improved Dab receiver). So far, my only conclusion was that if I'm forced to use menus to access my favorites stations on one of those Dab receiver, I could as easily use my iPad as a makeshift Internet radio. With a few extra bonuses: it doesn't cost me a cent more since I already own it, it has great sound and excellent portability, and I can connect my BT earbuds.