Bioware has said on a number of occasions, that they're currently treating the upcoming Mass Effect: Andromeda as the start of a new series, but that they're not announcing potential sequels any time soon.
Now, the game's creative director Mac Walters has said in an interview with Game Informer that you may want to hold on to your save file once you complete Mass Effect: Andromeda.
"I don't think it would hurt to keep them. Right now, to be honest, we are focused on this game, and as I've said to people before, we very much think of Andromeda as a series. What we do with that series is TBD at this point."
"I think right now, we know we don't want it to be a trilogy, in the sense of, we're planning this three-part story in three games. But that said, key elements like the Pathfinders, even the Ryders themselves, those are things that are going to make another appearance in the next game."
So, there's a clearly a "next game" here, but whether it ties directly to Andromeda is currently unknown. Still, now you've been warned - save your... save.