I would say No to the dead theory .
I also wouldn’t judge so much numbers of hunters as a gage as the numbers of muzzle loading hunters has always been low in comparison . Enter the modern inline and you have a boost . But just like with Archery, large numbers of compound hunters does not equate to the dying off of the traditional hunters .
While I do believe there is a reduction of strictly traditional muzzle loading shooters , I really thing what your seeing is more of a customer demand .
IE . In the 70’s there were many different production style guns on the market . People were getting all caught up in the centennial. Holly weird was cranking out fur trade movies …….. But what was also happening is that those people were getting interested in history to a degree .. So even though the buck skinning movement was going strong , inside that movement you had folks , digging , reading , researching and finding out that the production market was very much lacking in authenticity and in quality . Thus companies started to fall away . Eventually leaving only a couple to chose from . Thus as the modern movement came about, the customer base moved with it .
However at the very same time , the market for more authenticity and higher quality was growing to the point if you look around , its not hard to find someone who is either a builder or traditional gunsmith .the options of the guns to chose from is simply astounding.
Do they cost more . Yep . Ironically comparatively to wage , not much more then 200 years ago
Whole companies have sprung up . From lock makers , casting foundries , barrel makers , trigger makers , stock companies all the way to folks who run small businesses selling parts or completed rifles .
No one that I know is getting rich . But there is no shortage of work .

But that river that is customer demand changes so does they type of work . For the last few years I have seen a real resurgence of folk digging out their old production guns . Rebuilding or having them rebuilt . On the other side of the spectrum , even the custom market is changing in that more and more customers are looking and willing to pay the cost for a truly custom piece fit to them and done by hand . IE more and more people are beginning to make all their own parts by forging , casting . a lot more hand work is being done and frankly the quality of that work is in many cases astounding .

So as another poster said , all one has to do is look around . Do so and you will find a lot more then you think. Most anything from re-enactors who shoot guns ranging from lat 19th century all the way to the match lock of the 16th . Gun builders and smiths who can or do build everything in between . Hunters , Buck skinners and everyday folks who just enjoy shooting . To the long range BP muzzle loading folks .
Its all out there . Most times you just wont find them on forums that deal more to the modern side . For the most part I think we are just to different in the why of it all .

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