My plan currently is to ride out the 5dIII until I can go medium format. I don't really see how full frame is going to improve much from the 5dIII camera for the way I shoot, it can cover all of my needs now and do them all well....... but I want more MP to continue to rise in my landscape work. The D800 might be better for purely landscapes, but the focusing and just great through out controls of the 5dIII make it a joy to shoot for my non landscape photography needs. Even if they come out with a 40mp full frame, I'm not sure if I think increasing pixel density on the current size sensor is the way I would want to go.....guess time will tell.
My business plan builds a budget of 20k in the next few years to get a decent MF kit together. I need more stuff like this to come out and start to drive down prices so that I can cover it, because 20k for a phase kit doesn't get me far.
Layering multiple 50 MP uncompresed TIFF files in photoshop to do manual blending right now would bring my comp to its knees, so I am going to need a hefty upgrade there as well.
Exciting things.