Originally posted by SeaRefractor I agree that it's not likely to occur. But I believe plug-in replacements are possible. There are numerous examples of different parts manufacturers having drop in replacements. Check the number of threads out in Google scape that help smartphone owners determine which of two sensor products they have in their phone. Granted the optical precision or lack of it with a smartphone doesn't directly relate, but it is an example of purpose built drop-in replacements.
Since the CMOS sensor parts are manufactured with x-ray lithography and the tolerances are so small even new generation electron microscopes have difficulty viewing them, it's all a matter of Pentax providing the exact foot print and connector layout. Any electronics chip fab worth their salt should be able to provide sub micron accurate parts to the manufacturer's specification. Gone are the days of white lab coat engineers with calipers measuring the part tolerances, those are not even precise enough at these microscopic measurements.If a little dust or minor scratches on the lens don't show up in a measurable way on photographs, sub micron differences are not going to be detectable to any human eye.
Even with that technical possibility, I have been persuaded from the thread that Pentax with a cost perspective and the likelihood that Sony is hard at work to return to prior levels of production this wouldn't make sense. I also understand that you may have been referring to just taking any sensor off the shelf which would require a full redesign as you'd stated but my viewpoint was for a specifically designed sensor for Pentax.
First, Pentax doesn't own the sensor design so it can't give it to Samsung or another supplier to get a second source.
Second, knowing the layout of a high-performance sensor chip isn't sufficient. You have to replicate the process (fab equipment, chemicals, temperatures, pressures, times, etc.). In high-end chip making, they even worry about exactly which suppliers are providing the basic chemicals. Differences in minute impurities in baseline chemicals such as hydrogen peroxide or hydrochloric acid can affect yield and chip performance. It's the chemistry inside the silicon and layers that determines well depth (baseline ISO), read noise, leakage, line resistance, pixel clock speeds, etc.
The fact that Canon has tried for years to replicate the performance of Sony sensors proves how hard it is to make very large, high megapixel, high pixel clock, high DR sensors.