I must admit, this really doesn't excite me all that much.
There's more resolution to be had in the 135 format, yes. Probably even up into the 80 megapickle range.
But we're well past the 80/20 rule and firmly into the realm of diminishing returns.
Even theoretically, if you never print bigger than 24" x 36", even if you crop heavily, today's top-end full-frame cameras are more than enough. And, in the real world, those same cameras are just fine up to as wide as you can print on an iPF8100. Yes, a side-by-side comparison with such a print between a 5DIII and a D800 might maybe possibly reveal a bit more sharpness perhaps in the print from the D800...but only if you stand so close to the print that you can't even see the whole thing even if you turn your head.
...which is where the larger formats come into play. If a 5DIII or even a 1DX ain't gonna cut the mustard, then, really, neither is the D800 nor anything else in the 135 format. You'll need at least 645 format, if not all the way to large format, for the kinds of prints where the 5DIII is inadequate.
And let's not forget the cost, in terms of both performance and storage capacity. The new camera sure as Hell won't be 12 FPS, and it ain't gonna be 6 FPS, either. And you better plan on getting bigger and faster cards as well as a new RAID array to support it.
All for...what? 40" x 60" prints that look as sharp as today's 36" x 54" prints? Is that really worth it?
I'm sure, assuming the trend continues, that I'll eventually wind up owning a camera with more megapickles than my 5DIII. But, in all honesty, I don't see that happening until said camera has the non-sensor camera specs of the 1DX. Because, when it comes right down to it, it's not the sensor that's the weak link in today's cameras -- not by a long shot, and it hasn't been for quite some time.
Indeed, it's been that way ever since digital surpassed film, for that matter...which was somewhere around the dawn of the modern DSLR era, as I recall....