They already screwed up in making Zero Two the new and reborn Aruto by having him go back to Zero One, so it's now more likely that have Zero Two become the literal Nigou to Aruto's Ichigou.

...Of course that's assuming it is Izu! It's the most natural conclusion to me too, but I think this show (and franchise) has had more than one occasion where it forgones 'obvious' decisions in favour of worse ones, soooo my optimism is remaining cautious.

Barely any talk about the Saber portion here, It's all Zero One.

Bc Saber is still fresh

Also just isn't a lot to talk about. I'm sure it'll be fun, but the extent of what we know right now is "there's an evil rider, and the six characters that have teamed up in the show have to team up to defeat him". Not even a new form or anything right now. Just not anything to comment on, honestly! Looks pretty fun!

Yeah Saber's looks pretty standard in a fun way, there's just... a lot more to unpack with Zero-One's segment than Saber's.

I think Saber's twitter also teased that Falchion would show up in the show itself? Said something like "he will appear in tv too...?".

He'll either be just a cameo or he'll actually be mainstay.

Not the first time, remember kabuto, deno, kiva, decade scan show otherwise plot development like kabuto vs dark kabuto in the moon. Decade made a fake promotion trailer detailed decade vs evil decade. Ark01 was supposed to be Ark himself. That's why horobi and azu can become host for it in stage shows and as well as izu projections. They changed it to aruto, so anyone else uses it will be based on them like ark scropio horobi to noe kamen rider Eden. Yeah they're doing heaven and hell as well as classic ichigo Nigo poster promo because of 50th anniversary. If japan well japan is better off than Europe and USA, so they can make another taisen like level movie for sping.

Essentially, summer movie style. Except saber is taking kiramager mini slot. And 01 doing epilogue finale instead of self contained alternate what if storyline with vagued continuity. Kiamager might just get a vs/return two pack with next year sentai if there no toy sales.

Also, FYI final stage show ft fusion of Ark and Azu as red ark01 is subbed.

Idk what summer movie plans were. Some people did machine express shark was a movie toy, but they replaced garza mecha in the show as one of the traditional 4 megazord mecha. Falchion should just be called falcon since it look more like a falcon than ohoenix and even uses the orange color scheme. He might be coming back as one of those one shot villains like deatryuger from kyoryuger as well as kamen rider lupin in a small spinoff sequel.
I think the original plan was a reiwa vs movie like what they did traditionally for past ten years and recently in the Heisei finale trilogy. Falchion may or may not be in the original planned movie . He looks like another dark saber like calibur. They even replace calibur with him in the poster. The undying phoenix is overdone recently rider and sentais with wizard kyuuranger and kiramager respectively.

Umm, there’s no indication there’s any stage shows where anyone becomes Ark-One. And the producer said that Ark-One wasn’t even part of the plan for the endgame, he was just something they threw in to get to the final fight.

I think actually that was specifically Aruto becoming Ark-One. Ark-One was always supposed to be a thing, just not in the way it was. It was definitely planned early enough for not just those really-funny-in-retrospect scans of Zero-Two fighting it, but also for RKF toy production.