I favor either joining Akatsuki, or establishing Akatsuki-Leaf collaboration on Necromancy, or making Necromancy an AMITY affair. I would like Hazou to continue being significantly involved in Necromancy.
I disfavor any plan that reads like 'give up on participating meaningfully in Necromancy' or 'reject Itachi's offer, then come up with some way to flip the table on Akatsuki and murder them all before they can murder us'.
------- WHY WE CAN'T JUST FLIP THE TABLE ON AKATSUKI AND BE DONE WITH IT:
Leaf versus Akatsuki, as it stands right now, is unwinnable.
Leaf + all other villages vs Akatsuki is theoretically winnable, sure, maybe. But it also ends AMITY and ensures Leaf's slow partition by its neighbor states over time in the future.
Leaf + Akatsuki alliance is the only reasonable way forward, especially because that's what we already have, in the sense that AMITY is currently a load-bearing defense for Leaf, as Itachi has pointed out. Akatsuki may or may not need Leaf, but Leaf needs Akatsuki to survive, right now. If Leaf goes after Akatsuki, whether or not Leaf wins that fight, Leaf is already toast, because it's expending resources on destroying its own protection.
We need Hazou to be demonstrate that he represents a true asset to the project, not just a loose end whose ideology is mildly sympathetic to Akatsuki. We need both Tsunade AND Itachi to buy into this, in order for any effective alliance to form. But we have to form the alliance, because any other outcome destroys Leaf.
(It sure is a bad time to have a Severe Consequence from fucking up a seal infusion, which both prevents us from demonstrating our full potential and represents extremely visually salient evidence that we're not hot shit.)
Having Leaf and Akatsuki work together on this strengthens AMITY, which both Leaf and Akatsuki want. In fact, it's practically the ONLY thing they can agree on, at this point. I enthusiastically support the idea of making this whole Necromancy business AMITY affairs. This is what peace between factions who don't like each other looks like- unhappy negotiated compromises that nevertheless keep people alive and not fighting or plotting first-strikes against each other.
Also, I think we'd get along with Pain. What we saw of the guy in his climactic battle interlude made him sound like a guy with whom we agree on pretty much every ideological particular?? Pain's world does not sound that awful, and having Pain around to enforce AMITY would be on balance preferable to a world where Pain's not around, in my view.
Seriously, like, Itachi is literally the only person who's listened to the things we've said and actually approved of them, in a way that isn't just 'oh, how naively idealistic, but we'll humor you, you sweet summer child'. Guy's stating as straightforwardly as possible, 'you and I are ideologically aligned'. For the same reason that Akatsuki sees destroying Leaf as a waste, I would consider unilaterally destroying Akatsuki an equivalent waste. Literally nobody else in the entire setting has humored us! Shikamaru comes closest to taking our Uplift ideology seriously as an outsider, that's basically about it.
------- WHAT HAPPENS IF WE REFUSE AND STAY IN LEAF:
In the world where we stay in Leaf, we will need to debrief to Tsunade what just happened, and then one of two things is going to happen: Tsunade is going to tell us to drop Necromancy as Itachi ordered us to, or Tsunade is going to scoff and order us to push and contest the rift on our end.
If we push and contest the rift, that locks us into trying the various first-strike-against-Akatsuki ideas floating around. To reiterate myself: Even if we win, it's the end of Leaf. If Akatsuki goes, AMITY collapses, and Leaf immediately gets eaten by the circling hounds. (And if we lose, of course, Leaf is over, and we in particular are double mega over.)
If we just drop it, on the other hand, we stay safe and sound as a near-pariah clan lord of Leaf, and get to continue to doddle along on our path of doing mostly nothing while simply waiting for Akatsuki to win everything. We effectively declare 'I'm cashing out' and leave the table, giving up on the big prize that we've worked so hard for.
(And we sure do that a lot, don't we? We keep coming up with real nice shinies only for various S-rankers and jonin to show up, declare 'you can't be trusted with that, give it to me', and then we just roll over and give it to them because there's nothing we can do about it!)
Not only does giving up like this feel unsatisfying, but it also more or less guarantees we'll never ever get Jiraiya back- there is absolutely no chance Pain is going to just give Leaf an S-ranker back for free. Not even Konan would be so foolish as to suggest it.
This is why I continue to feel that the third way forward is the only reasonable way forward. Do the difficult thing and cooperate! It's especially difficult right now, given the whole Asuma and Kakuzu thing, but if Leaf blows up Akatsuki, Leaf goes next, and getting everyone involved to understand and accept this is critical. This is what peace looks like! Peace is when nobody gets to fully win and everyone has to settle for an irritating compromise that they don't like but have to grudgingly accept! Unilateral overwhelming violence being the first resort is what we ought to be trying to maneuver away from.
------- THINGS WHICH I DO NOT THINK WILL WORK AT ALL 1: UNKNOWN HAZOUWEAPON X
I guess we could also win in such a way that Leaf somehow becomes the new top-dog. Like, idk, maybe it turns out that with Lithosealing you can build the Literal Fucking Death Note in a month. In that case I guess Leaf would be safe. That, or every village unites to crush Leaf immediately before Leaf can zap all of their leadership and jonin and effectively conquer the world.
I'm not putting too much hope into this one, not just because I am skeptical that we can actually beat Akatsuki even if Hazou goes full Oppenheimer mode, but also because I am not convinced that Pax Konoha is qualitatively superior to Pax Nagato.
------- THINGS WHICH I DO NOT THINK WILL WORK AT ALL 2: STEAL THE RIFT SOMEHOW
Or we execute one of the various 'steal the rift' ideas floating around. I am also skeptical of this idea. It seems spectacularly unlikely that Akatsuki will let us near the rift again. I would not put it beyond Akatsuki to have just parked someone on the rift permanently, at this point. Maybe Konan. Definitely Sasori. Seriously, the guy's apparently studying ways to reopen that rift, it's implausible to imagine that he's doing that without access to the rift. I straight up expect that if we go there we'll find a fresh new minecraft-style wooden shack constructed out of local materials, sealed up to the teeth, with one Sasori sleeping inside and like five sasorillion puppets on patrol outside.
I also do not think this plan is particularly plausible or workable.
------- THINGS WHICH I DO NOT THINK WILL WORK AT ALL 2.1: SO JUST KILL SASORI THEN
Okay, sure, we drop (Unknown Sasori-Killing Weapon X) on Sasori, which kills him instantly.
We still die. The rest of Akatsuki is still kicking. They come after us and Leaf, game over. Any first-strike plan which does not take out ALL of Akatsuki at once fails. Even with success, AMITY ends and Leaf is left protected by nothing but the Akatsuki-killing / Sasori-killing weapon we developed and whichever S-rankers remain after the clash with Akatsuki. These things may not be sufficient to protect Leaf; we're basically just back at scenario 'UNKNOWN HAZOUWEAPON X'.
------- THINGS WHICH I DO NOT THINK WILL WORK AT ALL 3: UNCLE SNAKE SAVE US PLEASE
And, god forbid, we hand Lithosealing and/or Necromancy to Orochimaru, in order to get his apprenticeship, to get him onboard with whatever wacky anti-Akatsuki plans we come up with? Please Jashin no. A universe in which Orochimaru has sole ownership of the rift will be hellish. The guy will be able to reuse his test subjects! He'll escalate unstoppably in power! It'll be a humanitarian crisis, and ALSO simultaneously nobody will ever be able to stop him!
Seriously, any plan that considers handing those to Orochimaru is a complete nonstarter. By far better to just let Pain win.