Just a general disclaimer, as with all video game detail leaks, take the following with a grain of salt until confirmed directly by BioWare themselves. According to a post on Reddit, a user in March too a survey concerning the context of the next Mass Effect game, specifically the story and setting and where the franchise intends to go considering the supposed finality of the endings from Mass Effect 3. Instead of continuing the story of Shepard and the Normandy crew, the fourth Mass Effect game will instead focus on a new character, a pathfinder, who is charged with exploring the Helius Cluster of the Andromeda Galaxy, far removed from the events of the Mass Effect story and instead centered around discovering a new home for man in a galaxy so distant from home.
But the Mass Effect staples will still be there. The player will be in charge of a capable and responsive crew to embark on missions with and grow as a team, each with their own strengths and stories to play and experience. A wide array of planets and solar systems to explore and colonize, as well as a host of missions and gameplay elements for players to spend hours embarking upon. The post in question is detailed and involved, a lot of information for a leak, but before Dragon Age: Inquisition was announced a similar leak was made which turned out to be mostly accurate, so the claim does have some validity, however again, until a statement is made by BioWare themselves, be sure to take it all in with a heaping dose of salt.