I think that's overstating it. Fallout 4 was well received even if it was a little disappointing. So it really is just Fallout 76. They can recover from that, especially considering that Fallout 76 wasn't even a proper mainline sequel.
(Also, it is interesting to note that with the Bethesda purchase, Microsoft will now own "all" of Fallout and the "Fallout diaspora" caused by Interplay's death, as Microsoft already owned development studios Oblivion [made FO:Vegas, had developers involved with FO1 and FO2] and inXile [had developers on FO1, FO2, and FO-predecessor Wasteland 1/2/3, and was in a blood feud of sorts with Oblivion].)
Obsidian, the company is called Obsidian Entertainment.
That said, the folks at Obsidian (especially the creators of the original Fallout and New Vegas) have said they have no interest in doing a Fallout game. Tim Cain specifically mentioned during the Outer Worlds Q&A that the Fallout ship had sailed.
I think that Obsidian is better off doing non-Fallout things (and personally Outer Worlds is so much "Fallout Alternate Space Timeline" already that I'd much rather see them continue with Outer Worlds as the closest thing they ever again do to Fallout). It's just interesting to point out how many of the "Fallout birds" will come home to roost at Microsoft.