I'd put out a leak saying that we were making the reject ending canon, and the reapers completed their harvest of The Milky Way.
And let people chew on that awhile, until they realize that:
1) Canonizing an ending might not be such a good idea after all, and
2) Setting a new game in a different galaxy does not invalidate what you did in the trilogy.
Then follow that up by reiterating that we're not canonizing anything.
I'd make a reasonable effort to honor the trilogy's technology and lore, but would not allow it to be overly restrictive in what we can do going forward.
I'd make a list of some new themes I'd like to explore, and build the new setting with plenty of conflicts that would enable their exploration.
I'd put some fascinating new species in this new setting, complete with their own culture, history, and political intrigue every bit as interesting and appealing as the ones we've encountered before.
I'd build a dozen or two plants for pure exploration - maybe resource gathering, maybe some very different types of flora and fauna, some of which may be hostile, some may potentially be domesticated.
I'd build a story with plenty of choice and consequences, most of which would be fully realized within that same game. I would not allow the player to change the world state in ways that would create a lot of baggage to carry forward.
If the MC is well-received, I might use the same MC (and supporting characters) in the next game. If the same MC is used in more than one game, I would keep all LIs on the team, or at least available for recruiting.
I'd make the animations lean toward gender neutrality - it's easiest and least off-putting. I'd put all teammates in non-sexualized gear as the default, while supplying smexy options for players (and characters) who might prefer them. I'd keep the customization options, and maybe expand them.
I'd keep the SP completely independent of MP - no shared rewards, economy, etc.
Do that, and I might be willing to forego my general policy of never pre-ordering. 