I actually thought that Zeke had some superb plan, to save eldians from the rest of the worlds wrath, not making them go extinct. What a shitty character, and stupid, moronic motivations and reasons for his actions. This dude could've had so many layers, but in the end the guy is just a psycho. The same kind of assholes like in evangelion, who decide themselves, to know that the best of humanity is to turn everyone into some huge pond of primordial soup, when they could just off themself, and leave everyone else at peace.
(To be precise, I'm writing this comment with the presumption that this is all there is to zeke's true motivations/plans, since I have not read the chapters after this while writing this comment.)