I believe that the fact that is taking so long is because they are really trying to make it a story. Yes the *fapping* aspect of the game is good, but thats beside the fact that they may be really going for distance here. Now since they will be releasing soon we can either expect 3 things:
1. NIGHT 3 & 4: This will more than likely happen since we have the first 2 nights available, including an extensive update in the ARCADE MODE department
2. Solely introducing 1 night but making it grand:
Having this be a thing could potentially make more and more people want for more nights. Ultimately making people subscribe to the Patreon more and more which will lead to the development of longer, more complex gameplay.
3. INTRODUCTION OF NIGHT 3 AND PART 3 OF CHRISTMAS SPECIAL ANNOUNCEMENT:
This would be a really safe introduction to the next part of the series also given the fact that we are close to the holidays. I wouldn't be surprised if this was one of their top priorities.