My interpretation of "come of" in your context of "I don't suppose anything will come of it" is that the strike is pointless (from the woman's perspective) and that the train drivers are preparing their strike in vain. So I agree on your definition.
As for the man wishing to share the woman's optimism, I think he assumes that the strike will lead to something, but not in the characters' interest. Let's simply say they the train drivers prepare their strike for a better salary and working conditions, it means that the customers have to pay more, which indirectly affects both characters in a negative way. Just an example.