It sure would be great to have one of each!
I'm sure Canon will grant your wish and never produce a "one does it all" camera even if they cold - what's better than a customer buying one camera? Buying two :-)!
yea on that note... I wonder if Canon is deliberately segmenting the market, or just playing the R&D that they have in hand. For example, The 5D3 appears to optimize high ISO for wedding/event because thats what they thought people wanted. Then D800 came and showed that higher DR can be had at low ISO and folks started complaining that 5D3 couldn't do that too -- I suspect 5D3 is Canon's high-ISO optimization of their current capabillities.
So the next crop of Canon sensors will reveal their real capabilites, and telegragh the compromizes they must (or choose to) make, i.e the extent to which the 46.1MP beast has to compromize high ISO noise performance in order to produce better DR/shadow detail, or if new technology will make real and significant contributions in both areas.