It's fair to say that Fallout 76 did not get off to the smoothest start in the history of videogames. Even so, a recent rumor that it's about to go free to play, fueled by reports that physical copies of the game are in short supply in Australia (although the website indicates that there's still plenty of stock available, so make of it what you will) and wild speculation, seemed pretty clearly to be without basis. But it was persistent enough that Bethesda nipped over to Twitter to officially shoot it down.
There is no truth to this rumor.January 22, 2019
Bethesda hasn't commented further, and there's really not much more to say. It could happen someday, sure—multiple MMOs have made the switch over the years, some successfully and others not—but two months after release? Bethesda may have biffed the Fallout 76 launch pretty badly and in some mind-boggling ways, but it has to be aware that whatever goodwill remains between it and the fanbase would evaporate almost immediately if it transitioned from premium purchase to free-to-play that quickly.