Is Illumi soley here for Hisoka/Spider Buisness, or more
Illumi character has always been Zoldyck and Killua centred. Having him join the spiders when hes never had much importance in phantom troupe arcs seems to coincidental
Having him and Kalluto poentially die here also seems like too much of a waste, and is unlikely. Whether he is working with Hisoka or not, everything about his appearance here seems too unusual, especially how his last arc with Killua and Alluka ended. Him being in the troupe seems like a big misdirection.
Hisoka and Illumi have worked together a lot, but their arcs rarely revolve around each other, so i dont see either dying at each others hands, and its more likely they are teaming again for their own purpose. And if not, i see more likely that hisoka will die, (not that he is weaker), but he will likely be assassinated, or Illumi will finish the job that Chrollo started, as the prenup agreement seems more for Illumis favour than hisoka.
i feel like a proper conclusion to the Killua, Alluka and Illumi arc needs to happen. I hope it also links to The Kalluto wanting his brother back plot, or the idea that he envies Alluka