If we start the basic premise that the Island was divided by both Jacob and MIB, then we have one part of the formula. Jacob and MIB appeared to have a distant rivalry for control over the island. It was such a long rivalry, that it became a mere game to them. A game which may have had the ultimate ending of both of them ceasing to exist.
Jacob was the person who brought people to the island.
MIB was the person who challenged the candidates to determine if they would corrupt themselves.
But at the same time, Jacob was also manipulating people on the island - - - including the Others who apparently worshipped him.
As events played out on the Island, the candidates were divided by the Others (through kidnapping, deals, and deaths).
So a basic formula emerges:
CANDIDATE x (JACOB + MIB) = ISLAND x OTHERS
If Jacob and MIB were eliminated to zero, then NOTHING equals the Islands and Others.
But what if Jacob and MIB merged into "one" as two halves of an Egyptian soul in the underworld, then the formula turns to work out as
CANDIDATE = ISLAND x OTHERS.
For a candidate to succeed Jacob or MIB, he or she would need both the factors of the Island and the Others. A candidate cannot guard nothing, so the island must remain a physical place that contains displaced people.
Then we get to a similar vein with Hurley's guardianship. If Hurley and Ben take the place of Jacob and MIB in the equation, then we they become "one," in death, then a new candidate becomes a guardian.
