Yes, the immune system would probably be culled from our genome eventually if there were no pathogens left. It would be tremendously risky as a species, and al

Yes, the immune system would probably be culled from our genome eventually if there were no pathogens left. It would be tremendously risky as a species, and also very unfeasible considering how important microbes are to life, but you are correct in expecting an unused "feature" would likely be removed, as every "feature" has a cost. Much like cave fish that live in total darkness all their lives- their eyes disappear...