I'm not sure whether a 3rd one is due or not. It would be based on Eye of the Moon I suppose, and that has near-mythical status in the LOM world, as you probably know, as only a couple of early screenshots of characters were ever made. Not sure how much of the story Mike managed to remember and pass on to Chris Wild before he died, and as Chris works with Drew to ensure that the books follow the plots generally...
In other words I have no idea

I have not actually read the DDR one, only the LOM one. I quite liked it, but too many things did not fit into my vision of LOM lore which was very jarring (as you'd expect - Drew could not cover all of our visions of how the worlds are). Utarg especially, also Farflame and the use of the liths. Nice touch in the Forest of Dreams though. I got quite emotional !
How does the DDR book compare to the LOM book?