I’ve been to the future and there is nothing there. Image: Game of Thrones, Season 5.
The most spectacular example of the disappearing storyline problem is Game of Thrones. George R.R. Martin started work on the first volume in 1991 and it was published in 1996. There are now five volumes, the last of which still took five years to write and came out in 2011. The sixth still being written.