I'm pretty sure you are exaggerating by at least a couple of decimal points. As intriguing as I and other black powder shooters would find it I just don't see the Great Unwashed Masses flocking to the gun stores to buy such a thing.
Most folks won't trust a wedge locked style gun in the first place and a lot of others will look at the rear sight notch in the hammer and get an odd "WT....?" look in their face. At that point they'll set it back on the counter and wipe their hands on their shirts sort of like they just picked up something that might give them cooties or intestinal distress.
And while the Ruger Single Six has a pretty good market share and reputation I don't see massive numbers of owners posting up for the newly introduced Uberti and Pietta single action 1873's chambered in .22LR and with some models delivered with both .22LR and .22WMR cylinders. I suspect that this would be taken into account if we are expecting the Italian makers to produce such a gun.
It IS an interesting idea but it would at best fill a niche market. And good profit margins are not based off niche markets I'm afraid.
The idea is an intriguing one though. As a metal shop tinkering sort of fella that has a couple of .36 cap&ball guns I've been meaning to sell it makes me wonder if I could sleeve the bore with some rifled liner and bore through and sleeve the chambers and if the blade on the hammer would strike the rims..... oh wait, there's no recoil shield to hold the rounds in place. So I'd be looking at some major modification to the cylinder as well to allow me to install a donut rear section on a cut down cylinder. with a loading gate and firing pin.
Great.... just what I need. My To Do list is already so long that it rolls clean across the shop floor. Now I have to pen in yet another idea on the end of the already long roll of paper..... THANKS ! ! ! !