After spending the better part of 45 years in electronics manufacturing, from management to manufacturing engineering, some things that I read about developing and releasing a new camera body make me laugh.
Yes, Pentax and other manufacturers do use certain technologies in more than one body. Things like the main processor is just one example. However, short of re-using all of the molded plastic parts of the body and not changing the size or shape at all, all bets are off for much of the rest of the design as soon as you start changing other parts.
The K1 to K1 II is the sort of change that does work that way, and even that change was pre-planned leaving hooks and room for the extra processor.
Even after you spend months mocking-up and testing the look and feel of what the camera might look like (which always requires several rounds of marketing and management review and approval), just designing and tooling the molded parts takes many months and often, several iterations.
Also, since Pentax does not make chips and certain other assemblies like shutters, they have to work with outside contractors to either make what they want, or modify an existing design to the specs they are looking for. An existing shutter assembly might work as-is off the shelf, but the main processor would always have to be built/modified/coded to work with the rest of the parts in the system.
Cameras are very complex assemblies with hundreds of parts and a lot of very precise components that all have to fit and work perfectly along with being able to be assembled and calibrated with a reasonable amount of labor.
My guess is that, even with modern prototyping methods, CAD, etc., a camera development cycle is several years long.
However, I think that the release of the K3 III does bode well for at least one more generation of the K1. They have finally done the work to have a decent AF system, they can probably use whatever processor they used in the K3 III, so basic code is in place for things that are the same or similar (writing RAW files, Jpeg conversion, AF fine tune, shake reduction all would be very similar blocks of code I would think).
No manufacturer posts any development information, schedules or plans. You get what they choose to design and release based upon their view of what customers want and how the product will fit against the competition. Do bigger players release more products in a given time frame than Pentax? Yes, but they have all moved or are moving to mirrorless only (it is simply cheaper to make mirrorless than a DSLR and it has some well-known advantages, including robotic assembly, as well as some disadvantages) and Pentax has decided to stay and play in whatever niche market remains for DSLRs when the dust clears.
Hopefully, Ricoh will not decide to wave the white flag of surrender and will stay in this market producing Pentax products we all want and can use for the foreseeable future, albeit at a slower pace than we might want.
Lastly, is the pricing issue. I have been shooting Pentax sine the late 1970's. For many years, the brand was a significant value proposition, where the quality was as good or better than the competition at a lower price. About the time AF came along, they fell behind and went cheap, not trying to build products that competed at or near the top of the market. This never works.
Now, Pentax being still behind in some areas during the digital age, the consumers, conditioned to either the early value proposition or to the cheap years, are unwilling to pay higher prices for Pentax gear, often claiming the difference in price isn't worth the lag in performance. I have been listening to the price wailing for at least a decade, but I have also looked at the prices of things like the Nikon Z line (remember, mirrorless is cheaper to build than a DSLR) and Nikon pricing is absolutely eye-watering.
BH Prices -
Pentax K1 II, DFA 24-70 f2.8, DFA 70-200 f2.8 - $4700
Nikon Z6 II, Z 24-70 f2.8, Z 70-200 f2.8 - $6200
$1500 more for basically the same kit (yes, I know the Nikon will out perform the K1 in AF and perhaps some other areas like buffer depth/speed, but other areas do not favor the Nikon).
I wonder how many who complain about Pentax prices would run out and pony up $6,000+ U.S. for the Nikon kit?