I just recently made some dot3 normalmap tests in Blitz. It was said it's static. I found a way to make it react on a moving point light, but it used up 4 texture layers.
You're absolutely right, having a mesh or terrain animated may be an unnecessary load on the cpu, it may be possible to make the cubemap take the bumpmap into account, so you could have nice water simply by animating the bumpmap. I suspect that's how the water in copperlicht works, it's one flat plane. I yet have to try it in Blitz.