With This Is Us’ writers continuing to introduce more storylines regarding Jack’s past on their road to killing him off, it doesn’t appear that they’re planning for him to suddenly disappear.
That’s what This Is Us has teased anyway.
That same brother served with Jack in Vietnam, which is another part of Jack’s past that Milo Ventimiglia has expressed interest in the show covering in future storylines.
For example, it was revealed earlier this season that Jack had a younger brother who we never knew about before this season.