Jacob tells Hurley that Jack need to wreck the lighthouse & someone bad is going to the temple

At the lighthouse, Jack is sitting on some rocks on the cliff staring at the ocean. Hurley is still by the lighthouse when Jacob appears. Hurley thanks Jacob for the seven years of bad luck, then says that whoever needed to find the island won't be able to now. Jacob says that they will find another way to the island.

Hurley realizes that things worked out how Jacob had planned. Jacob says that Jack has something to do and he needs to figure it out on his own. He says that sometimes you can just tell someone what they need to do, like Hurley, but other times, with someone stubborn like Jack, you have to let them find it on their own.

Jacob then reveals that he needed both Hurley and Jack away from the temple, because someone bad is going there. Hurley wants to go help them, but Jacob tells him it's too late.

So who exactly is coming to the island and how will they find it? And what is the important thing that Jack needs to do? Is he the chosen candidate?