Another theory: What if you subscribed to my channel right now? 😳

Last ending would be kinda fire tho (edit: did not expect this to get likes)

Tanjiro should’ve moon walked out of the infinity castle 😂😂😂

Knowing muzan, he won't just take tanjiro's blood, he will absorb tanjiro to get all his power.

O-or...

In the beginning, it's shown that Nezuko is putting on the charcoal basket instead of Tanjiro, and after Nezuko says her goodbye, Tanjiro along with Rokuta surprise her to give a goodbye. Tanjiro's leg is injured, indicating he sprained/broke his ankle somehow. Nezuko continues the day like Tanjiro, only she wasn't able to help with the broken dish. Then the next morning Nezuko goes back up the mountain and like Tanjiro, Nezuko sees Tanjiro over Rokuta's body, and she runs up to the house seeing the rest of her family dead. Since she is not strong enough to carry Tanjiro, she puts him in the charcoal cart and descends the mountain for help. Then she slips and falls off the cliff, loosing the cart in the process. She quickly pulls Tanjiro out from under the cart and then he attacks her, then she meets Giyuu, and like Tanjiro, she pleads with him not to kill Tanjiro. Giyuu knocks her out, and then Tanjiro gets angered and protects her. Seeing this, Giyuu knocks out Tanjiro too, and puts a bamboo muzzle on him. He then sends a letter to Urokodaki saying the same thing, that Nezuko wants to become a Demon Slayer. The journey of Nezuko goes on the same as it probably did with Tanjiro, and she probably would too, master Hinokami Kagura.

So, no, Tanjiro would not die, not become evil, and everything would basically play out relatively the same.

To be fair, Muzan has been around for hundreds of years. He only made demons for a purpose. The hope they’d figure out how to conquer the daylight. So I don’t think if the demon slayers were destroyed the demons would spread and/or take over the world. Because I don’t think Muzan wants a world filled with demons. Where would their food come from? Also interestingly, Nezuko did end up being the first demon to conquer the light. It’s possible if they both were turned eventually her success would have been made known to Muzan and thus he would have found a way to beat the sun. After doing so it’s unclear what Muzan’s “ideal life” would be. Would he take over the world? I bet he would no longer have any need for demons at that point since he only made them to help his quest to beat the sun. So maybe he’d kill them all save except maybe make Nezuko his queen? Idk

Muzan actually targeted kamado family bcuz he knew their family know himokamikagura which is his biggest fear because of yoriichi.

wouldn't there also be a fourth one where Tanjiro and Nezuko's roles swapped, leaving Nezuko to remain human and Tanjiro to become the demon?

"Go ahead and live with your head held high! No matter how devastated you may be by your own weakness or uselessness... set your heart ablaze. Grit your teeth and look straight ahead." - rengoku

You know the last ending would be fire for everyone

For the demon slayer ending, tanjiro could also be hunted more by the demons cause just like how nezuko conquered the sun, tanjiro would technically also counter it. Making him being hunted quicker

For the demon ending, as tanjiro would likely conquer the sun as well. Resulting in not him being a twelve Kizuki, instead a test subject. This ending would go three ways, tanjiro being absolutely devored by muzan as muzan would try to use him to conquer the sun, muzan discovering how to conquer the sun through testing and him going to one of the twelve Kizuki. Or him completely rebelling and killing muzan, but him also disappearing.
The reason for the powerup is cause of the constant testing

“What Would Be Your Version If Chi-Chi Continued Her Training & Became A Z-Fighter?” - I absolutely hate that Toriyama put her behind and didn't make her a Z-Fighter. She had the most potential out of any other human on earth - more than Krillin, Tien or Yamcha. Imagine how much she could accomplish if she trained alongside Goku; maybe even mastering Kaio-Ken better than him, since she'd have to rely on it more than he would. As well as drinking the ultra divine water by Karin, having her hidden powers unlocked by Grand Elder Guru, and eventually bringing out her latent abilities by Old Kai. With her entire potential unleashed and her mastery of the Kaio-Ken, she'd be more than capable to enter the Tournament of Power.

What do you think of Chi-Chi training with Krillin, Tien, Yamcha and Chiaotzu for the year, while Piccolo trains Gohan? While Goku recovers in the hospital, Chi-Chi goes to Korin to drink the ultra divine water and has Goku train her in the Kaio-Ken during their trip to Namek - where she eventually has her hidden powers unlocked by Grand Elder Guru. But she doesn't have her latent abilities brought out by Old Kai until the Tournament of Power saga. Chi-Chi would also train with Goku and Gohan in the Hyperbolic Time Chamber, because the Cell in this universe would also have her DNA (and have the ability to tap into the Kaio-Ken). Chi-Chi would even help Goten and Videl with their martial arts and ki training.

I think that actually there would be another scenario which can happen. It was said in the manga that when Muzan finds out that Nezuko was immune to sunlight he was ready to absorb Nezuko to gain the same power. Muzan might just do the same to Tanjiro and then gain immortality (kind of)

It’d be cool to see Tanjiro do all that and then betray Muzan and become the new demon king

Kanoe does not use insect breathing she use flower breathing.

2:08  its actually flower breathing, bc kanao uses a sword, NOT A NEEDLE.

I WOULD LOVE TO SEE THE LAST ENDING ANIMATED BY SOMEONE

“Then the demon infection would spread all around the world” American Breathing Form 1 Verdent Bullets  American Breathing 11th form nuke sunlight barrage.

Even if uzui did survive the right with upper 6 (in the 3rd ending) then he still would’ve died due to the poison if nezuko wasn’t there to remove it

5:15 nah tanjiro would use plot breathing 1st form: resist and kill muzan in one hit