ISOCELL 2.0 improves the physical barriers around the pixels by replacing the metal materials with more reflective ones, further reducing color crosstalk and boosting light sensitivity. The new tech also allows for pixel size reduction without affecting light absorption coefficients, paving the way to 200 MP sensors and beyond.
https://www.notebookcheck.net/Samsung-previews-ISOCELL-2-0-tech-for-upcoming-smartphone-image-sensors.526128.0.html
...I remain skeptical that any proper stacking algorithm could make use of that much data.