robus - I have considered modifying a real-world Egypt map, or maybe Osirion. However, I don't get much time for that sort of thing anymore. But if I must, I must. I was just hoping that. in the year that this thread has sat dormant, somebody else might have put one together.
As far as Amonkhet not being an entire world, that isn't a problem. I actually have an idea to bring a couple of MtG planes together into a single world. The idea would take what is written in the supplements and basic wiki pages to create a past for a world that is actually a hybrid setting, in game. My mind went down that road because I liked the concept of having both an Egyptian and Mesoamerican civilization in the same setting. So, at minimum Ixalan and Amonkhet.