Recruiting Teams, the real substitute, and manipulation of the number 4 by lostaficionado

That the numbers on the cave are truly Jacob's numbers is debatable. As others have pointed out, Flocke could be responsible for writing these and be using the cave to manipulate Sawyer and whomever else to join him. There is no reason to believe that this is not the case. They've both been on the island long enough to learn about Dharma, the French team, Oceanic 815, and countless other individuals who were brought to the island (by Jacob). Whether these are Jacob's candidates for protectors or Flocke's candidates for a war against Jacob is yet to be determined.

Who is and is not on the list is puzzling. Why Faraday and Charlotte but not Miles or Lapidus? And of course, why not Kate? And why Littleton?

At least one person has noted the relevance of the 815ers identified as "the numbers" being in 1977. That is, except Locke (presuming Kwon refers to Jin). Whether or not their presence on the island preceding the crash (and during the construction of the Swan hatch bearing the numbers) matters, which it might, the fact of the matter is that Locke, number 4, is dead on the island. And has now been buried.

So if number 4 is critical to the survival of the island and the survival of the world as may be supposed, then the death of number 4 would be catastrophic. Just like the death of Sayid, number 16, would be catastophic according to Jacob's guitar case note. That suggests three possibilities:

1. Catastophe doesn't strike until the people representing the numbers are fully dead, soul AND body (including copies of bodies).

2. More likely, It's Locke may have been a candidate, but not #4. Jacob visited eight people in The Incident, six of which (at least) are in the numbers (Kwon might mean BOTH Kwons rather than just one.). Kate was the real #4 but Flocke, knowing about the relationship between her and Sawyer, thought it more effective to keep her out of the recruitment and erased her name, assigning Locke the number. Possible evidence: while everyone else Touched By Jacob was alive and well at the time of his visit, Locke was possibly dead and revived by Jacob. I'm going with a one of these is not the same and that's the red herring approach -- Locke was never #4.

3. Most likely, KATE is the substitute. She was brought on to Oceanic as a backup in case she followed Jacob's prodding to "be good." Something so critical as saving the island had to have a backup plan in place in case something went wrong. Kate could step in to replace one of the numbers if something went wrong. She is the replacement #4. That explains her notable total absence from the board when so many others were present. Rose would have been a darn good substitute, too, but complicated since her island existence is unknown. If Kate is the ONLY remaining substitute, then the actual death of Sayid would truly be a catastophe. Given that the episode was titled the substitute, and John Locke was only a substitute teacher for three minutes of airtime, the significance of the episode being titled "The Substitute" suggests something deeper -- that Locke's death creates the need for a substitute #4.