Some people state that they hope that Canon will stop increases in the number of sensels, or even reverse it. I want to know if their claims have a good, sound reasoning behind it, or if it is folklore....
Yes there is good sound reasoning based in physics and mathematics. The more signal you have in a given measurement the higher will be the SNR.
Yes I am aware the topic of larger pixels is highly debated hence my attempt at making a precise statement about the technical measurements rather than "image quality". Yes, under some ideal conditions a higher resolution measurement of a signal and some clever mathematics can result in a signal that is equal and sometimes superior if resolution was a limiting factor. However, those conditions are not present in digital images where there is low signal levels such as shadow areas or in any low-light shooting. NR software can only improve images so much.
Sweetspot... how did he define that? And what did he mean by highest offered resolution. The spatial resolution of a typical P&S scaled up to FF is something like 200MP yet that is not offered, why? The bottom line is that there are trade-offs in optical systems and image sensors.
Fair enough... marketing cannot be trusted on its face. But to say they could save costs by using an archaic process I think is a stretch and marketing itself is a huge part of the reason for offering increasing megapixels... it sells more cameras and perhaps with the current limit of technology they already went a little past the sweetspot at say 24MP APS-C.
Can you further explain your comment about "analog amplification ISO".