I doubt he'll really die. But, I could see Luffy basically "faking" his own death.
There has been a lot of "death flags" for Luffy in the manga. And he's been going into "old man mode" a lot, recently. Using his powers is clearly wearing on him. So, I feel like that has to pay off somehow. But, I think it'll basically result in us getting a "death scene", .which basically turns into a fake-out.
Luffy wants to be the most free person in the world, after all. And that can't really happen after the story is over if he's being hunted by the Marines. He's still a pirate, after all. Even if the World Government gets reformed, Luffy would still be a criminal in the eyes of the law.
But, I could see everyone kind of pretending to go along with the idea that Luffy is dead, as a excuse to let him get off scott free. Just imagine everyone humoring Luffy while he's wearing a fake mustache pretending to be someone else, like back on Sabaody. Everyone knows it's him, but they all go along with the ruse because they're all thankful to him for saving the world. Something along those lines.