If I were being cynical, I'd have assumed that your description above was the case earlier. I've been giving them credit for actually knowing that the ending has serious problems as a story in general and as an ending to this story in particular - your explanation there does not. Whatever the motivations one assumed, my conclusion if your explanation were true would be that Leviathan were more evidence of how major the writing failure around the ending is - particularly since nothing that Leviathan expounded upon could accurately be called a "cliffhanger." The parts of the (original) ending that would fit that description would be the questions of what happens to galactic civilization at large, and your team in particular, after the events shown, which Leviathan doesn't (and couldn't, given what it covers) touch.
Which has what to do with any of this? Those are separate game series.
A direct sequel has never been intended - Shepard's story is over, remember? Any further games will be entirely new stories, simply using the same setting.
Zevox