Todo's boogie woogie has powered up a lot, and that's an understatement.

So, is Gojo back or is it Kenjaku in Gojo's body?

Kenjaku's dead, Jim.

I'd be willing to bet that it's Takaba or something

So Yuta didn't cut Kenjaku head just with Takaba distracting him, but also with Todo's help, it was strange indeed that a moment Yuta was slashing Kenjaku from behind him, then when Kenjaku turned towards him to stop him with gravity Yuta disappeared and then appeared behind him completing the slash, like he never moved. The onomatopoeia of that panel is actually the same of the new Boogie Woogie with that instruments and even in this chapter they said Todo perfected this technique at the lake with Yuta, Yuta and Kenjaku were close to a lake when he delivered that blow. So Todo tested his technique on Yuta and Kenjaku by swapping them at the moment of the slash, hence why Kenjaku despite reacting was still caught from behind.

Kenjaku is dead for good, he got his brain stabbed and he also transferred Tengen to Sukuna exactly because of that. It's not Takaba because I think he si actually dead and also because in this situation I doubt he would think it would be funny for Gojo to be alive, too sinister for him plus bringin him in would make the situation too messy to handle for Gege. And it's not Sukuna seeing things because right now he was about to win the fight with his domain, he is in poor conditions but he is not about to die like Nanami, and in all other scenarios they were all already dead, in perfect shape and the scene was dreamlike, not in the middle of the battle inside the smoke with everybody wounded and covered in blood. Also is not another technique because we didn't see anyone with illusion-like skills currently alive and it would be stupid to introduce a random CT out of nowhere right now.
There are only two possibilities and both with a possible explanation:
1) That's not Gojo but his body indeed and maybe they placed something that could move, for example they could have put Panda's core inside him to act as a decoy at the best moment to shock Sukuna and give the final blow to take him down.
2) That's actually Gojo and there is an explanation:
a) Gojo knew Sukuna and Kenjaku had a binding vow, he was worried about that and that's why he chose to postpone the fight, it would have been far more convenient to him to fight a 15 fingers Sukuna rather than a full power Sukuna.
b ) Gojo said that he went through a special training for this fight, what it could have been? The most of us thought that it was being inside the prison realm since he used that knowledge to alterate the dimensions of the domain to a basket ball, but Gojo was in the prison realm before, he had no idea what was happening while he was away. So what did he train for? Perhaps expecting his own demise he trained by having someone else actually kill him to train his RCT to come back even in the worst possible scenario not involving his brain destroyed and the possibility to have Shoko fix his body if the damage was too heavy for him to regenerate solo?
c) the most important, when chapter of Gojo's death came out, Gege commented by saying that after a 2 week pause it seemed that he forgot to draw a chapter, now what if that's actually a clue? I mean the previous one ended with Gojo in perfect shape while Sukuna was leaning against a wall with only hand he was left with, the next moment after the airport scene, Sukuna is right in front of Gojo, no wall close to them, Gojo is cut in half. We didn't see the world cutting slash, how it happened, if Gojo noticed it but it was too late, nothing, which is way basically everyone were disappointed by it, even Gojo haters, because everybody wanted to SEE the final blow. Now Gege commented it that way, maybe because when Sukuna used his world cutting slash it happened something that we were not supposed to see? That would explain why he did that choice, still awful but understandable. Also it would mean that we would actually get, maybe already in the next chapter, the actual end of that fight on real panels, not off screen anymore which would give us proper closure to that climax, even if in awful retard.

Honestly right now I'm still sceptical about Gojo being alive, but I would appreciate if that would mean seeing the end of the fight between him and Sukuna. Also if he were alive, it could be a real change for Gojo because he would return not anymore as the strongest, but just Satoru Gojo since by his own admission Sukuna is the strongest ever so he wouldn't see himself anymore as detached from others as he did before his death. Anyway next chapter could be either the best or the worst thing happened to this manga, Gege is really risking a lot. I'm curious.

The true reason Yuta killed Kenjaku was to copy his parasyte ability and borrow Gojo's body?! I don't know how it works but now suddenly dialogue boxes of Sukuna became far more bigger with his body moving a lot when compared to the previous rounds.

Honestly I didn't expect Yuta to copy the brain transferring technique because I thought that cutting down the brain would have prevented that. My initial idea was that Yuta would have had a big fight with Kenjaku and then he would have copied Geto's technique to tame Tengen an prevent the merge. Kudo to Gege for choosing this strategy.

Now the point is: in what conditions is Gojo's body in terms of CE? And Sukuna domain will last again 90 secs? If it is so, Infinite Void has a chance to win, especially if Yuta, like Kenjaku, absorbed all the memories from Gojo's body about how he fought Sukuna inside the reduced domain. However Sukuna will probably do the same thing he did before and break his domain from the outside, but Yuta already knows he can so... who knows. Anyway how the next five minutes to Namek explosion go will determine everything. If Yuta copied technique will be interrupted he will die, or maybe he will live on as Gojo but will lose Rika and his Copy so he won't be able to return to his original body.
Honestly the main reason why in the previous post I said I was incline to believe it wasn't actually Gojo but a decoy with his corpse was just one: the first thing Gege would have shown us in that situation would have been Gojo's crazy smile, not his eyes.