An old post of mine:
I have seen a few ''Luffy will die at the end'' threads but I have rarely seen any ''Why Luffy will not die'' threads and I don't remember any up here.
I know that there is a possibility of Luffy's death at the end, this are just the reasons why I think he will not die:
1. Luffy went on an adventure to follow his dreams and be a great pirate, he does not want to be the Pirate King to become a legend, he just wants to be the pirate king and have the freedom that comes with it, and beind dead makes that a bit difficult
2. Many say he will die because of gear second and the Iva treatment but the first one was said by and in the middle of a fight with Lucci, imo it was a simple exaggeration device to build up the tension (it is used in all forms of literature and especially in manga, I have yet to read one without it ... it is a fast and simple tool to raise the stakes and build up the tension), we now see that after the TS gears don't really affect him anymore, not to mention that if that were a fact Chopper, who was raging about his treatment of Ceasar, would rage at Luffy 24/7 about the side-effects.
The 10 years poison stuff was build up by Iva as something horrible and exaggerated in a similar way to build up the sacrifice and tension before the Ace rescue and even further add to the desperation of Ace's death ... but in reality Luffy recovered very quickly and just had to eat some meat ... all he would have needed to do after that is lay down for a while and he would be his kid self in no time ... and after all that there is still Chopper, one of the best doctors, and (provided their ties last) Law, who can literally cut him apart and treat him methodically.
And if all the above reasons (on the ''sickness'' matter) are not enough for the end I say killing of your main character (and one of the most beloved/iconic characters in manga) after (what we can assume will be about) 1200-1300 chapters with an illness is very disappointing and completely anti-climactic.
3. Many people parallel Luffy to Roger and therefore ''Luffy will die just like Roger did'' ... except that makes no sense, Roger died because he failed, he reached Raftel and they learned the true history but Roger died before he could (like WB said) carry the weight of history on his shoulders and challenge the WG so he, as a plot device for the entire story of OP, died and started the great pirate era, he made sure that someone will find One Piece and do what he could not, which is challenge the govt. If Luffy succeeds there will be no need to start an great age of pirates
4. The revolutionaries are so far the biggest direct opponents of the world govt, judging from their goals and plans they will have a major say in reforming the system once the final war is over, why does this matter in this thread? ... well if what WB is indeed true and Luffy will play a large part in fighting the corrupt government and if the revolutionaries will play the part they were set up to do there is no way that Dragon (or any of the revolutionaries) would after the victory label Luffy as a criminal and execute him
5. Oda does not like to kill of characters, but that in itself is not my reason. The next reason is that I am quite confident that Luffy will not die before 1. Dragon, 2. Sabo, 3. Garp and 4. Shanks and as I said before, I doubt all of them (+Luffy) will die
6. The last (but not least) of my (main) reasons (I can remember at the time of writing this ) is that simply that if Luffy died people would rage, he is perhaps the most recognizable character in Japan ... they could go on strike

. Shonen authors do like to give the readers what they like, not exactly what they want but they write the story with the fans in mind (I might be exaggerating a bit but in essence it's true)