I will say this again that would be the biggest waste of a DLC because the next game would be great if it was about the Second Great War, a DLC wouldn't do it justice.
I didn't say that it would be a good idea for a DLC, I just said it is likely.
I somewhat agree with you, especially that the Second Great War would be a good next game but its rare for a company, especially Bethesda, to carry out a conflict into the next game. They would have more time to make a better storyline, combat, missions, etc. if they continued it to a next game. Once again, it is rare for Bethesda to carry out conflicts into future games so I wouldn't expect that.