Many Fallout fans have been wondering what is going on in Bethesda's mind, whether Fallout 76 will have mods and if we'll be able to play it solo. Definitive answers to those questions came from Bethesda during QuakeCon and here they are.
Fallout fans want their sandbox experience with the ability to modify it with the stuff made by the good folks who put some hours, days or even months in at Nexus mods. With the announcement that Fallout 76 will be entirely online during E3 2018, it is reasonable many fans were worried if their experience will be impaired by the "games as a service" mentality Bethesda are embracing with this one.
The short answer is yes, your experience will be hampered. Ever since Fallout 3, every Bethesda entry in the series has been a mess at launch and even after releasing GOTY editions which fixed mountains of bugs. What made these games amazing is the creative freedom everyone had with mods and Fallout 76 will not have them at launch.
This much has been confirmed, but the news of mod support on private servers will bring joy to many fans. Then again, there is another Howard-shaped curveball, meaning that mods will be there only on private servers.
The notion of private servers should put fans' minds at ease, since these servers will offer both modding and a true single player experience. Now, there is still no mention whether they will be available on launch and there is no talk about whether they will be free.
Technically, Bethesda never stated they wanted to monetize private servers, but considering Fallout 76 is there specifically because they wanted to monetize the franchise more via games as a service, it is not hard to imagine them charging a monthly fee for the servers in the future. Or why did you thing The Elder Scrolls Online exists?
The fact that there will be no Fallout 76 on Steam is another indicator that Bethesda want to squeeze as much money as possible out of the game and its Creation Club, so it's still possible paid mods are an option for the official servers in the future.