Hey! Thanks for showing interest and sorry for the late reply.
Yes that is pretty much my idea, but the difference to overworld is, that there are still structures, ores (in clusters, not as a whole layer) and lava oceans, which a normal superflat world usually doesn't have.
The nether fortresses should spawn blazes and wither skeletons, just like a normal fortress would. It can be the same, large structure you can find in a normal nether world, but it could also be a smaller, "custom" structure (I have no idea how difficult that is to implement, but it's not not my #1 priority to be a custom structure).
If you need any more details or have any questions, let me know and thanks again for showing interest in my idea