True, but it's obvious they plan on extending the game further with DLC. Even at the end, it's sort of implied Shepard lives and there's more stories to tell. Questions in the series aren't a bad thing either. It gives more power to the player. Instead of trying to get inside Bioware's head, players get to think for themselves about the story.
I don't mind seeing the series come to a close. We got a trilogy, it was great, except for that Galactic Readiness BS, certain answers will get filled in DLC, and Bioware can move on to new IP's rather than make a sequel to something that wasn't intended.
They don't plan to extend the game with DLC though. Their plans for DLC are for post-end game missions. Eg: Take Back Omega. The game boots you before the point of no return for a reason.
Shepard's survival in the destruction ending was, as Walters put it, just a tease of 'hope'.
They don't want post-ME3 games of any kind. This may change now, and it might have changed if under the pressure from fans, but that was their intention.
Like I said before, I don't think they want to flesh out the universe. They are done with that kind of game.
Get ready for one shot stories that have no repercussions outside of that game.
It doesn't help their case, though. Even if their goal is to make a bunch of Uncharted-esque Mass Effect games with self contained stories, it is in their best interest to keep the universe open.
Hypothetical: Reapers die, Shepard is dead, the universe now fends for itself. Premise: civil war between the species in a post-war environment where resources are scarce and alliances begin to crumble, as the species of the galaxy try to rebuild their homes while burying the dead.
They could have basically gone "nuts to trilogies" and still furthered the game universe with something
fresh. Something interesting, though familiar. And, by keeping the universe active, they have a hook for essentially unlimited material to keep old fans interested, and to milk the universe with comics, books and other crap.
Limiting themselves to a specific time frame does them no favours regardless of the kind of games they want to make. It limits their source material, questions the commitment of series long fans (who are easy money), and backs them into a corner they may need to retcon themselves out.
If all they want to make is Call of Mass Effect or Uncharted: Mass Effect it would still more beneficial to give their universe room to breath.
What they've done is just...dumb. Hurts the franchise, hurts the fanbase, hurts everyone.