An Amazon listing popped up with a December 31, 2019 placeholder date and a full retail price of $59.99 for a new mysterious game. Since the internet did its thing by noticing the store listings and spreading the news, they have since been taken down. But not before Wario64 found the associated teaser video that clearly looks like some sort of Fallout-related thing.
Check it out.
With no real details to work off, the new game could be anything. As a full-priced release it could be some sort of Fallout collection - with remastered versions of either (or both) Fallout 3 and Fallout: New Vegas coming to current-gen consoles. After Fallout 76, the odds of it being a new full-sized Fallout 4-style adventure, single player, are somewhat low but also possible.