A factor influencing our perception of whether or not sensors continue to evolve and improve is the recent lengthening of the generational cycle. At the height of the DSLR era, the typical generational cycle for flagship cameras was 4 years with mid-cycle refreshes. We saw this in the Nikon ecosystem with the D3, D4, and D5. There were four years - almost to the day - between the release of each. Mid-cycle refreshes included the D3S, D3X, and D4S.
However, by the end of the 2010s, the interchangeable lens camera (ILC) market had seen seven consecutive years of declining sales and manufacturers adjusted, accordingly. Nikon did not refresh the D5. Their next flagship body was also their last DSLR flagship, the D6 which was released 4 years after the D5.
The mirrorless era of digital ILCs is still young. Yes, we've had mirrorless ILCs since the Panasonic G1 in 2008, but Canon and Nikon only joined the party in earnest less than ten years ago. Based on the sensor design and specs in the Sony AII and A9III, Canon R5 and R5II, R3 and R1, and rumors about the upcoming Nikon Z9II, manufacturers appear to be moving toward a 6- to 8-year generational cycle between wholly new sensors and processors in flagship bodies.
Some may misconstrue this as evidence that sensor evolution has stopped. However, as evidenced by resolution, data processing, autofocus, burst rate, buffer, and video performance gains, evolution continues. But the pace of evolution has slowed. We're not seeing completely new flagship products every 4 years. The market can't sustain the financial investment required to maintain that pace.
It'll be every 6 years or possibly 8 years between successive generations of flagship bodies...but the evolution of sensor technology continues.
