Well, instead of all the pitiful groin-licking, let's examine why this is happening.
1) Economics has always driven publishing. Not many people are willing to lose money in order to publish something. If gun books were selling, people would be lined up to publish.
2) Most books - gun books or otherwise - are poop. The art of writing has gone downhill greatly. I read 3-4 books per week; I seldom make it through a book without seeing grammatical errors. Additionally, their content is also lacking - short on facts or compelling text, long on rambling opinions.
3) Shooting guns is a lot like sex in that it's OK to read about someone else doing it, for a while, but much better to be actually doing it. There's not much new under the sun when it comes to gun writing. Gun writers usually are scrounging for something, anything, to write. Good books are driven by subject matter waiting to be told.
So is publishing falling apart because of the internet or because the content has gotten so middling?