WARNING: MAJOR SPOILERS FOR SKYRIM, MINOR SPOILERS FOR MORROWIND

Okay, so, "canonically", the Dragonborn was a Nord. Statistically speaking, this combined with his starting game experiences would suggest he would join the Stormcloaks. There's one possibility.

Next, it could make sense for the canon ending being the truce on High Hrothgar. Peace on both sides seems optimal.

Another, more brainmashing ending is that there was another Dragon Break, and both sides "won". These seem pretty complex already, but if Bethesda did it before, they'll probably do it again.

What do you guys think?

Nobody's gonna know until TES6. And the starting experience doesn't mean a thing, he could've been pro-Imperial from the get-go and still joined them too.

yeah, not all Nords are SC supporters