It's just the supply chain backlog. Like with ammo, makers have had to prioritize and have chosen to focus on the biggest sellers. They certainly focused on 9x19 more than on 357 Magnum, so while it would seem there would be less demand for 357, there has also been a lot less supply of it. Similarly, the cheap pocket revolvers generate the most demand, and that's what makers have prioritized in the supply chain.
The makers will not lose sales to the people who want a kilobuck revolver, for whom there is no substitute and much less competition. The demand for Colt Pythons for example is durable. The people who want them and will buy them will wait and that demand will abide all the while. Someone who wants a cheapo pocket gun, if they can't get one, they'll buy different one that they can get. This isn't just characteristic of revolvers, but all kinds of higher-end guns, particularly where the maker has other product lines they could prioritize. Consider all the high-end lever guns (and I say that relatively speaking). You can have all the Henrys you want, but otherwise you'll have to wait. The thing is, the people that want a Marlin or a Winchester will wait. Ruger's Pinetree Casting is no doubt busy cranking out frames for guns in a more competitive market space and Miroku is probably focused on the Browning shotguns that sell in higher volume and with greater margins.
Some maker's supply chains may not overlap products for which there is higher demand. I mentioned Henry already. We could suppose that Colt's revolver production isn't affected by high demand in their AR-15 pattern rifle lines. Even so, there seems to be good availability of Pythons in 3" and 4.25" barrels, so if the King Cobra is receiving lower priority, it's probably in deference to the higher-margin Pythons.
A glut is coming. We're already seeing signs of it. The makers that learned from past experience and are deft at navigating the business cycles were carefule about ramping up capacity. Retailers who have been putting in orders for more and more product as their shelves lay empty for the better part of the last two years have started to take delivery of some of that stuff -- right when demand is waning, due to the effects of inflation, higher interest rates, and a slowing economy.
Unfortunately, I'm not predicting high-end revolvers dropping in price. It would not be sustainable to produce them and sell them at a loss. Production will remain subdued (like an OPEC production cut) to keep the prices up. The availability should improve though.
