At the end of the movie Bones creates a serum from Khan's blood which he uses to revive Kirk. Do they now have the ability to cure all disease and even short term death? They could start harvesting Kahn's race for blood. It was a big enough temptation for one man to kill in order to save his daughter imagine the possibility of being able to eliminate death.
As for the effect of the serum, it look like it could cure any disease. McCoy also literally revived a dead Tribble with a simple blood sample. However, they had to freeze Kirk in order to preserve his brain function; that is the only limitation we are made aware of. The other details about how it works and its effectiveness are unknown.
As for the nature of Bones's serum, given that a girl was cured using unaltered blood, the serum could be literally a substrate of Khan's blood. So the simple, but somewhat unethical solution, would be to use the frozen members of Khan's race to produce serum from their blood.
Since Tribbles are an alien species, it may mean it's not a property of the blood itself, but it may be an additive in the blood that cause the regeneration. From that point, Bones may have found a way to synthesize this additive, allowing its production from scratch.
With all that known, an elegant solution would be to create a race of genetically enhanced Tribbles that would be used to mass produce that serum. But nothing in the movie indicates it's McCoy's solution.