Putting aside all Theories & Facts & Hints, people need to understand that this isn't just an Ordinary Sub-Plot
This Traitor Problem is something that Oda is giving a lot of time and lot of importance & focus
So logically, the Conclusion to this Sub-Plot should be a great Plot Twist & a Major Story Reveal to justify the Time & Effort Oda put into it
So for starters, Traitor should be someone Important in Wano Saga, someone with enough Build Up & Connection to Alliance to make this
Sub-Plot Work, that's why the Traitor can't be someone like Shinobu
You think Oda mentioned Traitor in Zou Arc so that it will be revealed +100 Chapters later that it was Old Just Introduced Ninja Shinobu ?!
The best Candidates for Wano Traitor are one of Nine Red Scabbards, Law, Carrot
Momo & Hiyori are the representatives of Kouzouki Family and the center of the Wano Arc so leave them aside
So let's see what this Traitor knows ?
He/She knew Zou's Location/Viver Card, knew only Raizo is in Zou, Yasuei Identity & Location, Hiyori is Alive and in the North, Udon was taken over by Alliance, and all Alliance Plans
There is only one Character that knew all of this and much more, who is so far the most mysterious of them all, the one who didn't do anything for Alliance, and seems the most useless of the bunch, the one who have ability to exchange information easily
It's none other than Kanjuro himself !
The only thing that bothered me about this idea is that it was hinted by Toki & Orochi that Nine Red Scabbards will be his Downfall and will face him under Full Moon and defeat him, so Kanjuro being a Traitor would contradict this and break their group
However i think Oda hinted at something in latest Chapter, when 7 Red Scabbards + Momo & Shinobu were walking, he said these 9
In other words, even though he could have used any word to describe them, he instead chose to address them by their Number
IMO this was a hint that 9 Samurai who will stand against Orochi aren't necessarily the Nine Red Scabbards, they can be any 9 Samurai from the Alliance, which furthur proves the idea that Traitor is among the Red Scabbards
This way, when Kanjuro is shown to be a Traitor and dealt with (Possibilities are endless), Oda can choose someone else to be among the Nine who defeat Orochi (Obviously Momo)