Case used to make a lot more patterns than they do now. Then they introduced their "Vault" program where they would do a rolling retirement of some of the less popular patterns for a few years at a time. The idea was to build up some scarcity demand and then have something "new" for people to look forward to when they pulled a pattern out of the vault, and put another one in.
Last year or so they quietly discontinued the Vault program and at the same time permanently retired some patterns, including the Elephant Toe, Eisenhower, and Copperhead, others. They have been introducing new patterns, usually as a result of Tony Bose designs, so maybe net-net it is the same. I don't know if their Barlow pattern was officially retired but they haven't made new ones in a while.
Ones I no longer see in production include the Humpback Stockman/Whittler, Pocket Hunter, the '27 Small Stockman/Small Pen, the '25 Small Coke Bottle, the Barlow, the others I mentioned above. Additions have been the Sway Back Jack/Gent, Back Pocket/Panama Trapper, Sowbelly Stockman, Tear Drop Jack, perhaps some others I have forgotten.
I would say that the partnership with Tony Bose has been probably the biggest influence on Case's choices of patterns, as well as their own sales numbers for patterns and handle materials that do well.