As part of yesterday's Fallout Day livestream — which included the announcement of Fallout 4: Anniversary Edition — Bethesda announced a released window for the native Xbox Series X|S version of Fallout 76.
Coming "early next year", Fallout 76's Xbox Series X|S upgrade "will take full advantage of their [current-gen consoles'] hardware capabilities". The team didn't go into anymore detail on the upgrade's new features for now, but we'd expect to hear more about them in the coming months.
"Early next year, a native version of Fallout 76 will be coming to Xbox Series S and X and PlayStation 5. This update will take full advantage of their hardware capabilities."
If we look back at Fallout 4's current-gen upgrade — which arrived last year — we can expect boosts to resolution and frame rate, and hopefully a native version that takes full advantage of the Xbox Series X|S SSD. The Fallout 4 upgrade also contained a 40FPS mode for 120Hz displays, which wouldn't go amiss here with Fallout 76.
What we'd love Bethesda to avoid here is a repeat of the Fallout 4 current-gen launch. The update for Bethesda's 2015 RPG arrived late and notoriously buggy, before multiple patches aimed to fix things up. Here's hoping next year's Fallout 76 update is a smoother release overall.