See my Fujifilm GFX wish list.
The comparison is imperfect—it cannot be perfect given different aspect ratios, lenses and their distortion, etc, but the tripod position was fixed and it is remarkably interesting to compare the two—42 megapixels versus 50 on different sensor sizes.
What happens if Sony delivers an improved sensor and improved (less 'cooked') image file quality at, say, 72 megapixels? That would be interesting at full resolution, let alone the implications of oversampling at 72MP and then downsampling to 50. For now, the GFX looks highly satisfying.