As a marketing guy, I'd say this about the product; unless there is a readily identifiable demographic of thousands willing to buy at a sustainable price right now, I would not do it. I would also ask the question "Is it safe?" Based on my previous articles, my answer to the second question is "Yes, it's as safe as any cap and ball revolver". The problem with that is there is a huge degree of mythos and negative PR involving the design. This means that the majority of buyers would be experienced shooters who would rely on their knowledge and honed abilities to avoid shooting mishaps.
The original launch of this design by Palmetto Armory was a disaster. I understand recouping the expenses of tooling and die making but the $1695 price tag was enormously prohibitive. At the time when CW rifle muskets were selling for $600-700, this was selling at a price point that even the most dedicated reenactors and BP enthusiasts would balk at. Despite the price, the quality was so bad that horror stories across enthusiast websites put out the message loud and clear. Occasionally, I hear someone say "I shot the Palmetto Arms Colt revolving rifle and it worked just fine, but those are at extremely few.
In order to make it work, a massive campaign on brand awareness would have to go out (eg. all BP shooter related websites, magazines, catalogs like Cabelas, Gander Mountain, Dixie Gunworks, etc.) Social media and youtube videos would need to be produced demonstrating the longarm's safety and to spark interest. Lastly, it would need to hit the market at a more reasonable price ($800-1000) but even with all this, there is a lot of data revealing that only a few purists would truly be interested in buying. Even if I had the money to do this project, I'd even be hesitant.
-Dave