During his Reddit AMA, Kevin Smith revealed that he's postponing work on Clerks III in order to make Comes the Krampus. Comes the Krampus is a horror anthology film that came out of one of Smith's podcasts on the Smodcast network. Smith was originally planning to work on Clerks III after finishing his first podcast based film, Tusk, but said that he decided to move forward with Comes the Krampus over Clerks III in an attempt to keep trying new things:
So now that TUSK is nearly done (we still have our Guy Lapointe scenes to shoot this month), the idea was to gear up for CLERKS III. But then I started thinking "Isn't that stepping backwards? Like literally?" While I love it with all of my heart, CLERKS is my past. It's how I got started. And I'm just getting started again, after taking 3 years off, certain I was done making movies. TUSK represents something bold and new. No matter how bold I make it, CLERKS III will always have a number in the title. It will never be new. It will rock, I assure you, and it will be a worthy final installment in my mini-mart magnum opus. But it's predicated on something I did a long time ago. I wanna keep moving forward. SModcast Pictures is becoming exactly that: we're starting to make movies based on podcasts. TUSK was the first, and now COMES THE KRAMPUS will be next: https://silentbobspeaks.com/?p=1075 Now, at this point in time, nobody but me can make a CLERKS film. But ANYONE can make a Krampus picture. So before anyone else does, I figured it's time to keep moving forward: we're gonna shoot COMES THE KRAMPUS in April, before CLERKS III.
So it looks like fans dying to see Kevin Smith complete the Clerks trilogy will just have to wait a little longer.