https://toonado.com/adult-swim/primal-creator-genndy-tartakovsky-on-season-3-shifting-from-anthology-format-to-zombie-horror-a10009
>"At the end of Season 2, I talked about Primal becoming an anthology. So, it's going to be different characters, different everything, just following the core idea of Primal, which is not a lot of dialogue. It's visual storytelling. It's visceral. It's raw. After developing for a little bit, I realized I missed Spear, and I spent 20 episodes having the public love him and having the audience really like the relationship with him and Fang. And then an idea sparked that I could do more, and Spear became a zombie."
>Though Tartakovsky has kept most story details under wraps, he did reveal that Spear and Fang’s offspring will appear in the new season and play a pivotal role in the unfolding narrative.
I guess he wasn't forced to abandon the anthology.