Calm down, more pixels does not automatically a better camera make, or even a better sensor. How about the color fidelity? the dynamic range? the high ISO? And what's the framerate when the onboard processor has to write files that big? (definitely not gonna be an action camera) And can your computer handle processing files that big? Will this sensor have the 'banding' issues that plagued the previous 5d sensors?
With that pixel pitch I'd worry about some detail being lost to diffraction limitation at tighter apertures even with the very best lenses, so don't stop down to far in those outdoor shots, and with 50mp, you'd better have a very good tripod and use mirror lockup or you'll pick up motion blur. No doubt thousands of facebook wanna be "pros" will buy it without a clue how to use it, and wonder why all their pictures don't look any better then they did with a Rebel. I suppose 50 or even 60mp might work OK on a 36mm sensor (no way in an APS-C sensor) but anything more then that and you'd better go to medium format, and a used Pentax 645D can be had for not much more then the new 5ds. I've been tempted to get one myself since I could use my old 67 lenses on it which have just been collecting dust for years since local 120 E-6 processing went extinct. Also I see Canon has followed Nikon's example of charging more for the version without an AA filter then the one with it. I still don't understand how less can cost more.
Meanwhile as a longtime A-mount user (since 1990ish) I'm still stuck wondering if Sony will ever build a worthy replacement for my beloved A900, or if I should just buy another A900 for whenever this one dies.
Not to rain on your parade, I'm sure it's fine, fine tool. I just don't get that excited about new cameras these days though. The lens will always be the biggest factor when it comes to image quality and most serious photographers have 5 times as much money invested in lenses as they do cameras, and unlike camera bodies today, lenses don't get superseded by a better model every year. In today's photography world, bodies come and go, lenses are forever.