There are alternate possibilities but they aren't the reality until it happens.
The clue is in the 'sometimes', but the tide will come in again tomorrow, I can guarantee that.
That doesn't prove anything. He wasn't, so he was, so I am. Anyway, my grandad's were too old for either war.
These are all conjectures. There is only one past, so there is only one future for that past. Up to now, at least.