So we are about a week away from release now, what are the chances Nintendo announces a season pass? They announced the Zelda one 2 weeks in advance and the Mario + Rabbids one was revealed 5 days before the game came out, so Nintendo has been making a habbit of announcing it at the last moment recently (I know Mario + Rabbids is ubisoft, but it's season pass layout mirrored Zelda's exactly along with the Mario Kart 8 one so I feel Nintendo had more of a say in it.)
I feel like Nintendo won't bother with a Season Pass for Mario Odyssey. For some reason, platformers like that seem like the kinds of games that can easily be delivered as "content complete" without needing anything additional.
Obviously I could've said that with Zelda, and it still got DLC. Still, if Mario Odyssey is a big enough game, I think it'll be fulfilling without additional content, and I'd probably prefer that EPD moves onto something else right away. We'll see how Nintendo approaches it this time, as opposed to how they approached it with 3D World (a game that I believe was actually somewhat fit for additional content thanks to it's streamlined design).
Sometimes, I enjoy the idea of post-release content. More for multiplayer games like MK8 and Splatoon. Other times, I'm fully content with one, complete package that I can play and put down once I'm done. Maybe Nintendo feels like a single release is enough with Odyssey, maybe not. I can't say for sure.