Omfg, the other comment section is cringeworthy, lot's of people playing themselves: "There's no way Tanjiro can come back now!"
1- The oni disease curing medicine already exists.
2- Muzan's statements has already been proven wrong more than twice in the story(the entire progression behind Nezuko pretty much counters Muzan to a point that challenges his own existence)
3-Tanjiro is not your average brat, by all means he is already being treated as a Pillar, if talentless Genya can survive demonization, so can extremely talented Tanjiro, moreover he doesn't even lose on the mental side of things.
4- Tanjiro is in the middle of the Sun breath development plot. He is literally the only character in there who cannot die until this is solved, because no one else has any clue about the sun breath aside from him
5-His death would actually be a sign of bad writing, as it wasn't even due to a fight that he would go down, but just because he tanked some of Muzan's spilt blood from wounds caused by him and other pillars. It would be a death that contributes nothing to the plot. ONly for shock value, and we all know these kinds of deaths are not an element that has ever been present in the story.
From both narrative and world building perspective, and even using elements already present inside the story, I simply cannot see Tanjiro's death. I've already given 4 ways Tanjiro can use to get out of this in the 5 points above. Not a single one of them came from asspulls, but clear story elements most of which have been shown in this exact arc.
@Tranloc7 no poison works this fast, not even Muzan's blood. IT took several days for most of the Oni to become what they were. A poison doesn't need to corrode the entire body for it to kill a living human, it only needs to cause enough damage.
@Winterspring I sure hope that doesn't happen, I don't want to give the author any ideas on how to use a longstanding and utterly irritating trope of having the Villain complete all his plans and be defeated afterwards only to have the author asspull a miracle to save the character or object that was sacrificed by the villain to fulfill their plans.