Frankly, I don’t think Diisuke is going to do another Eirin Doujin, let alone another Touhou Doujin. He seems to be focusing on single images for the 2hus and is working on another Doujin at the moment. I also remember him saying that he’s done with the Eirin Saga (if not, the next one will be his last one) and his interest in 2hu is slightly waning. I could be wrong though, and maybe he’ll make the holy grail of hentai. Until then, I’d hold your breath.