The world will end. Fact.
I often say to people that the sun will swallow us up, but that the heat increase way before that time will end life by itself.
Then, during some writing and researching, I decided to look up astronomical predictions, and found that there is a potential for a massive gamma ray burst that could wipe out all life on earth long before the sun swallows us.
"Long before" is probably as relative as it gets, and I don't have the numbers here, but yay!