I dont see there being a new coder unless the current one quits on his own accord. The artist might be the public face of MITY but I dont know its ever been said that its strictly his project (meaning he could get rid of the coder if he wanted). Its been the two of them for years so I dont really see them changing that when theyre halfway done with the 4th book.
That being said, the Artist really needs to tell the coder to get his shit together. He has a pretty consistent track record of falling behind on updates meanwhile the Artist will finish what they need to do for the current build and already be working on scenes for the next one. Obviously we dont know whats said between them behind the scenes but if the artist has tried to get the coder on task then it clearly isnt working.
Its honestly more sad than annoying, this is one of the best western porn games out there right now and the updates are almost always top notch, but they have a nasty habit of failing to meet deadlines and lengthy periods of radio silence leaving patrons in the dark (the artist is a little better about this, at least). Considering we're now 10 days into October and still no word on when the update is even coming out, they should give the update to anyone who was pledged last month regardless of their October pledge (or lack thereof). While each update sometimes takes a few days more than a month, 10 days (assuming it were released today) is too much, especially since it was promised "in a week" more than a week ago.