An online fallout could be the best thing ever, but I wasn't too taken with Elder Scrolls Online so I'm wary. Something pretty ruthless and emergent like Sea Of Thieves would be a great direction to take an online Fallout game in for me, where the full world is open to everyone from the start, and players can kill and rob each other whenever they choose and alliances are verbal and temporary. Give people the power to build settlements together and trade and you'd get communities and economies forming over time which would be fantastic, it'd be a super interesting social experiment as well as a game.