Now, here is a 1969 sale list from ESCO:
I don't know if you can make it out but under "sports cards" the prizefighters and wrestlers are the only available sets. The other non-sport topicals give a clue. The Beach Bunnies (pin-ups) are a set I have handled quite a bit (yeah, insert dirty joke here) and they are the same stock and printing as the BW boxers. As are the later Jets versions.
So, by 1969 the company had stopped making baseball cards but was still willing to crank out boxing and wrestling cards. Judging from the populations, I don't think there were many takers. My purely unscientific observation is that the sepias are the easiest to find, followed by the greenies, and the BW are the toughest. Well, the slicks are the toughest but they aren't 'cards' per se.