I started in 2018 and went through 2019 trying to keep close to a zero-sum policy for knife acquisition while somewhat consolidating my collection, selling off multiple lower-value knives to fund the purchase of higher-end pieces. That's one way to go to buy something like the Quantum, particularly as you seem to have acquired "quite a few" lately.
I haven't heard anything about a discontinuation of that model and it would surprise me if they did that as the F95T still seems to be one of their most popular designs. I didn't see anything about it over at USN where Tom the official Shiro rep hosts, contributes, and moderates. There are only four official outlets for the knives worldwide and I just checked them all--the Workshop's website doesn't have any Turtles shown in the For Sale section, Rezat lists the model as "Not Available", the official dealer in CA shows it as "Sold Out", and only Knifecenter lets you put an F95T in your cart with the caveat "Typically ships...within 1 to 2 months". That last quote leads me to believe that the knife will continue to be available. My suspicion is that with so many new and recent models coming out of the Workshop that their production capability has been concentrated on those and the stock of Turtles has been allowed to temporarily dwindle in the meantime.