Who said that digital camera technology has reached its peak? Resolution is always a combination of sensor pixel count and lens quality. If the DR of this new Canon is equal to that of the Nikon D810, when the image is down-sampled to 36mp, I'll buy one.
It won't have as high a DR, unless there is a breakthrough in stacked well depth capacity. The 13248 x 8832 pixels will presumably have a pitch in the order of 2.71 micron (if the sensor is 36 x 24 mm), but down-sampling should create some benefits for smooth tonality and reduced noise. I haven't done the math yet (because I do not know how efficient the lossless compression is), but 14-bit or 16-bit ADCs also make a difference. But I do not know what Canon uses.
For 90% of the users we already have enough resolution, but there will always be those who can benefit from more detail, not only for larger output with less stitching, but also if they end up with lower resolutions after down-sampling.
Cheers,
Bart