So the bottom line from credible sources is that this adapter is still in production. Either Pentax has cut back on production or the demand is so high that there isn't enough stock to go around. Or perhaps they are having QA issues since it appears to be made outside of Japan now.
Whatever the reason so much for the cynical remarks by another poster in another thread that B&H would continue to list it as back-ordered to the end-of-time even when the item had been discontinued
So those who are willing to wait and not be gouged by the inflated prices used ones go for should continue to check the Pentax Webstore or keep their back-order notification active on Adorama and B&H.
Fortunately I purchased one right after the price reduction and they were in-stock after being back-ordered for a few months. It has been in and out of inventory 2 or 3 times since then. I wouldn't mind another one to leave on a set of bellows.