Well know about some real people that were done that way and the books about them gone for about 30-100 sites till the end. Example: Alexander the Great -poison Julius Caesar -knife Napoleon - assumed poison Abraham Lincoln -shot John F. Kennedy -shot
As a backstory, the MC body somehow dying isn't necessarily uncommon, if it allows for the possession by the MC soul. Though they rarely happen in sight of others, because that would make it harder to explain. As for it actually ending the entire novel... then according to manga standards, it was axed.
R.I.P Yang Wen Li, Ctholly/Willem. It's not dying. it's how you die. Burn bright and may the universe never forget your name. Salute!
There's no point if MC dies anticlimatically, it means you shouldn't have chosen him as the MC just because you wanted to try something new or realistic. There's a reason no one has done this. If you don't like MC's having plot armor then choose someone who will simply survive 'till the end. You have other options such as multiple MC's, MC dying but passing the torch, MC dying for however long you wish(while developing other characters) and being brought back. So you're talking about trasmigration which pretty much most of web novels and fanfiction are based on...
How would you know it's an ongoing plot? If the protagonist is on a quest to kill a dragon, but ended up being killed by a bandit somewhere, that may be intentional. It's like how we all want to be rich and piss on the peasants, but most of us will die without ever smelling enough money or piss. We all will die in the middle of our quest just as easily as God throwing a dice and landing a 1. Ai-chan can easily imagine a story where a knight goes to rescue a princess but on his way, had sex with a whore at an inn somewhere. He contracted STD which accelerated quickly and died without even reaching the princess's prison. Turns out the author never wanted the knight to rescue the princess and the whole story is just a cautionary tale of the dangers of unprotected sex.
There is also this method of forshadowing example "end scene " THE DEATH take first place in book after this go the narrative way back in time like how much is needed from birth, last 3 weeks, today, few hours...and the main story is about how it came to this. There is also the option of crime scene and a inspector try to remake what happend but this would put the "book" into a multiple MC category because the real mc would be the inspector and the death one would be used only in flashbacks there are many ways to put a MC death on the end. The more i think about it Romeo and Juliet is a classic example of how it work.
I read some CN like that, but a true story suddenly ending midway would be a hiatus or the author died.