I've built a collection of nodes that show the material I want in material view, but renders ignore both the noise texture and the mixed colors. The render does show my height offset texture map. To clarify, I add the texture map to the noise so I can adjust the noise that otherwise generates the continents below. The elevation offset texture is also in the screenshot, and it appears to be what the render view is showing in plain blue.
I also have other texture for biomes, which generate the desert and forest regions, using mix nodes.
And actually, what I really want to do is bake the material result to a new texture (ideally without shading, but I do want normal maps and color, and to arbitrary new UVs). But that seems to go through render to do. If I can bake the material without going through render mode, that's okay for my current needs also.
But both "Why doesn't this render?" and "Can I put my material onto a texture straight from material view mode?" are both meaningful questions here. And I haven't been able to find answers.
I've got some nodes collapsed into groups here, sorry, but this shows the overview of what I'm doing, with material view at bottom left and render view to its right:
The comment from @cegaton explains my main problem. Here's a partial solution to my problem:
I now just need to find a node to mix the displayed shader output with the normal map.
Following advice from @cegaton again, I feed the height directly into the final Displacement, but then the material view (where I do the editing) no longer works (and note that the right-most Diffuse BSDF is unused both here and in the previous screenshot):
Anyway, at least I have an easy way to shift back and forth at this point (by switching the final feeds), so maybe that's what I have to go with for now, if there's no way to combine a shader input with a height map in a way that works for both material and render views ...