I can't see the 5D3/X getting an articulated screen.
From what i can gather it was never meant for photo shooters but the video side of things.
The reason being that with the 1D and 5D series for video most people use devices such as the Zfinder, Red Rock EVF or external monitor.
But when you take the video capabilities to the mass market. The people that normally buy cheap video cameras for $200. If you offer them an articulated LCD they have a device they are used too. These are not people that will spend an extra $300 on a Zfinder or similar.
Don't get me wrong you can use them on the 60D and lower but thats not who the marketing department was aiming at with this design.
Guess thats another one of them damn video features that no one wanted in their DSLR cameras.
If anything i can see the next 7D gaining the screen and then even being re named the 70D, yes it would have the same build quality and specs as we have come to know in the current 7 series, it will just become the high end crop body (Seriously why do 7D people get so defensive over the idea of changing the number??).
It would actually make sense to do this to make the XXD series worth while again.
I guess some think its a video feature, but, I see it as a still feature, since I don't do video.
Being able to frame and compose low angles or in tight places, over the head shots, etc can be a valuable tool. Otherwise, you can just point and hope you have what you want in the frame. I am not able to get down low to frame a photo, and, taking a ladder along is obviously impractical. Many photographers use a wide angle lens, hold the camera up high, and crop later. That worked with the old press cameras and their 4X5 film.