Well, considering it's so far been a two year project and what he's gotten done over what's left to do, I'd say in another two years before the final product is slated for distribution. He's gotten a lot done despite his setbacks, and this project is clearly his longest running ever. MIKO, his other most ambitious title, took 2 years to complete. His ever adapting artstyle might have been the reason while he abandoned the Ninja 1 Remake, which is sad, but it's also wonderful that he can acknowledge his skills are growing exponentially.
So far the game is missing a lot of stuff including: unique enemy molestation attacks, the capture map where the girls go if you're defeated, art for the Miko and green haired mage, skill books, etc. What's interesting is in his older 1.0 version the NTR facial expression sex attack was in the game, you just couldn't access it normally and had to go to a test map to see it. In his latest demo it was removed completely. Also, some screenshots show skill books being picked up, so I wager he has a bit more done then he's shown so far. Mephisto is a hard worker, if he doesn't suffer from 4 more computer breakdowns, mental fatigue, illness or what have you, we should see the game done probably next year.