Long-standing rumours about Starfield suggest that the game will be set predominantly on a gigantic space station, with the player undertaking missions and solving quests in the standard Bethesda manner. At key points, the player can also leave the space station and travel to other planets to undertake extra mission objectives. This makes the game sound very similar to the Mass Effect franchise from BioWare, although presumably Starfield will use Bethesda's traditional first-person perspective and will focus more on solo play than forming parties. The same reports claim that Starfield is set in the far future of the Fallout franchise and may link that universe to the Elder Scrolls setting, although this sounds less likely, especially after Todd Howard's insistence that this is an all-new and totally new franchise.
Starfield has no release date as yet, but late 2019/early 2020 seems feasible given that the game has been in full-time development since Fallout 4's release in 2015, and was in pre-production for some years before that.