It is somewhere between just been started and not yet finished. It should be the next DTG route released after SEHS so it won’t be more than a couple of months away.
Someone asked DTG Protagonist that same question on last week's roadmap stream and, putting on his poker face, he said something like "it's coming along just fine" and nothing more. So your guess is as good as mine, though it has been "in production" since September I believe.
Well, while you're waiting, you could buy TS2021 which includes Clinchfield among other routes. That version is excellent and will only serve to whet your appetite for "the real deal" in TSW.
I use TS2021 all the time, not really the dark side in my book, I find both sims to have their pluses and minuses ... both well worth the money for entertainment value if you enjoy train simulations. It is sort of fun to compare similar routes in both sims.
