"At a distance only a good displacement map maintains it detail level longer, as both others, bump and normal map are fake and do nothing in 3D space.. "

Evidence please?

I see the opposite. I see that normal maps give the same answer without need of interpolation from a well-done mipmap. Which means that detail is retained over a greater distance. A corollary is that a normal map will produce slightly more detail given the same memory commitment, i.e. resolution of image.

Here's my evidence.

Up close.

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Renderosity forum reply notifications are wonky. If I read a follow-up in a thread, but I don't myself reply, then notifications no longer happen AT ALL on that thread. So if I seem to be ignoring a question, that's why. (Updated September 23, 2019)