The Last of Us has established a number of organized factions and militarized groups that would be great to feature in its currently untitled multiplayer spin-off, and that is only taking from the factions that have been revealed in the few areas The Last of Us has explored. It is entirely plausible that remote regions in the United States could have other extremist groups that behave radically, and there are always people desperate to get by during the fungal pandemic. It will be interesting to see how many of these dynamics are reflected in the multiplayer spin-off.