The world in my campaign is always moving. If the players fail/ignore a plot point, they will encounter the consequences at some point. Case in point, the players were in a harbor city, when they noticed one of their npc allies meeting with some sinister looking women.
-They spied on the suspicious characters, and noticed them receiving a mysterious box from the npc. They were unable to stop the villains from getting away with the box. The box contained the skeletal remains of a notorious pirate captain. The villains were able to find them due to the players removing the bones from an unscryable location, and giving them a proper burial, at the request of the pirate captain's daughter.
Result: Many days pass. Meanwhile, a powerful necromancer acquires the skeletal remains from her minions, and reanimates the pirate captain. They now have an undead pirate captain to deal with.