It's not just the prepper message boards that are dying due to lack of interest. Some of the same is happening to amateur radio. It too, is being replaced by social media.
Right now there is a serious proposal floating around to take a huge portion of 2 meters and turn it over to business interests. They claim it is "underutilized spectrum".
In my area many of the analog voice repeaters are going silent and what activity you find has moved to the new digital modes. Many ARES / Skywarn groups have become inactive, but you can still find them on fakebook posting selfies from their last club picnic. These same people can't be bothered to key up on the airwaves.
"The time for war has not yet come, but it will come and that soon, and when it does come, my advice is to draw the sword and throw away the scabbard." Gen. T.J. Jackson, March 1861