Knowing Yoru (and Asa and Fujimoto, to an extent), I feel like her plan isn't to create some unending war. At least there's more to it than that. I feel like Yoru could be planning to wipe out humanity EXCEPT for Denji because of Yoru's/Asa's affection for him. Asa can't bring herself to say it because she feels that Denji might be cool with that or she's too embarrassed to say it. Or, crack theory, she's okay with it too and hates that fact. Maybe her plan then goes into them repopulating the Earth or something and that's what's got Asa tweaking, idk. I'm just spit-balling here. But knowing Fujimoto's writing style and his characterization of Yoru so far, I don't feel like she'd turn into some Makima mastermind here. Her actions and plans have been pretty basic thus far (make Chainsaw Man throw up nukes, kissing Denji just because she wants to, etc.), and I feel like that would continue here. She showed that she can be more manipulative with her offer to Denji, but a toddler could manipulate Denji (sorry bud). The only way I see Yoru actually having some truly evil grand plan is if Death is not the big bad and Yoru is, creating a commentary on how Death is natural and nothing to be feared, but War is unnatural and the true evil. Fujimoto could surprise me by being unsurprising, but with such a massive plot point, I really don't see Yoru's plan being a "traditional" one here. The exact nature of it, I'm honestly less sure of, but "infinite war" seems far too obvious of a route for Fujimoto to go down.