I’ve read and heard several camera reviewers say that they think the M4/3 system has pretty much reached its maximum resolution with the new 20 Mpixel sensors in the Olympus Pen-F and the Panasonic Lumix GX8. I say that’s hogwash.
If you look at Sony’s 1 inch sensor found in the very popular RX100 line and in some other cameras from other manufacturers, it has 20 Mpixels and provides quite decent noise performance.
This 1″ sensor has a surface area of 13.2 x 8.8mm or 116 square mm. A M4/3 sensor has a surface area of 17.4 x 13mm or 231.4 square mm, pretty much exactly double the surface area. So they could easily bump the M4/3 resolution to 36 mpixels today and maintain a lower pixel density and better dynamic range and noise performance than the 20 Mpixel 1″ sensor.
Personally I think they should go up to 24 Mpixels on the next generation M4/3 sensor and stay there for a while, taking advantage of better dynamic range and noise performance as sensor technology continues to improve. I really do not see the need to go any higher than that.