@ Arcian:
Thanks for the point by point response. I respect your pov. Even though I completely disagree with your conclusions. I am not trying to change your mind. Or even influence it. I am suggesting that those of us who like or love ME Trilogy see all of this very differently from you and others who share your pov. First and foremost is the fact that ME, in all of its past, present and future iterations is simply a science based fiction game. A completely made up, fictional universe which Bioware is unfolding in episodes/sagas/trilogies/DLC addons. Anything is possible within that kind of creative construct. A scenario can be based on fact, assumptions, myth, history or any other context. And be completely legit. Your own buy-in to the story (post the ending) actually validates that reality. The ending ruined it for you. For most others it meant nothing (or something very good). Following is my response to your points.
1. "And let's be real here, there's only so many times you can replay the same, slightly differently colored ending. Shepard's dead, s/he ain't coming back. There won't ever be a "new Shepard narrative".
Maybe. Maybe not. But you don't really know that. He got resurrected from death once (that we know of). He got cloned (Citadel DLC). And Both he and the clone had vague endings. I bet your conclusion would be different if you could see into the future. And find out that the Mass Effect Saga with its multiple Trilogies was always about the ongoing creation and proliferation of life throughout the Cosmos "Universe, Microverse and/or Omniverse". With all of its multiplicity of potential "Parallel Realities".
2."Sure, but I'm not expecting it to be even remotely good."
You buy-in to a game on a very different basis than me. I don't mean that as criticism. Only a fact which suggests that I never knowingly buy a game that I don't expect to be "remotely" good. So I will make an assumption that I concede may be completely wrong. I think your plan to buy it is because you are intrigued about the unknown potential of its premise. Especially in relationship to a much bigger ME picture that you don't want to miss.
3. "My sole expectation was that they wouldn't destroy the entire galaxy and ruin opportunities for future Mass Effect stories set in the Milky Way. An expectation that's so narrowly specific it's almost impressive how they still managed to let me down."
That may have been your expectation. But it sure wasn't mine and millions of other players. But neither conclusion really matter. Because they didn't destroy the entire galaxy or ruin opportunities for future ME stories in the "Milky Way", as you surmise here. They didn't even do that in the 4th cataclysmic "Destroy" ending which you are referring too. Because even with that scenario; life in the Milky Way Galaxy persisted. Only the Mass Relays were destroyed. The Reapers harvested what they wanted from the dominant MW species. And left promising others to grow and proliferate. Indeed, the great Game, "Kingdoms of Amalur-Reckoning" was based entirely on such a Mass Effect premise (in partnership with Bioware). It started out with a mystery and remnant technology from a Mass Effect "world long lost from events that occurred in a very distant past". If you have not played that remarkable game by the defunct 38 Studios/Big Huge Games, then you missed a gem. Because it was a direct descendant of Mass Effect 3 in the Milky Way Galaxy, that went down a completely different path. And left a lot of questions unanswered. The concept, commerce system, decision tree and combat style was very similar to ME. But it had very unique differences. I won't spoil it for you. But I loved that game. It is Skyrim/ME long. My over arching point is this. Nothing in the MIlky Way was destroyed except an order. Which left completely open the opportunity and possibility for an infinite number of new orders to emerge from an infinite life perspective.
4. Shepard's dead, s/he ain't coming back. There won't ever be a "new Shepard narrative".
You are flying blind and completely lost on this one. The only safe thing to say is this. Shepard will not appear in ME-A except for vague references, if Bioware is smart and elusive (which they are), Andromeda needs to stand on its own merit. And present/solve its own mysteries. Bioware can always bridge the realities anyway they want to in the future trilogies. With any kind of narrative they want. They don't need a "Canon Ending" to even do this, as most of the flawed ending crowd assumes. They just need vivid imagination and creativity. Because the bricks are already laid. All 4 endings are organic. Because we were allowed to play them all. So a fictional universe has already been created whereby they are bridged into one. You just have to imagine "Alternate Reality Physics" to grasp that possibility. Even "Indoctrination Theory" is a potential narrative within that possibility. Here is reality. If there is lots of money lost by not bringing Shepard back. Or lots of money gained by bringing Shepard back. Bioware will be all in on that potential. And they left lots of bread crumbs along the trail in the original trilogy to execute such an outcome.
5. "Short of retconning the endings or canonizing one of them, they're not going back to the Milky Way. Ever."
Refer to number 4 above to ascertain why I think this assumption is not really even probable. Ever is a very long time. I suspect we won't even approach that major milestone on this game in your lifetime.
6. "You give BioWare waaaaaaaaaaaaaaaaaaay more credit than they deserve. They couldn't even plan a single trilogy in a coherent, consistent manner."
You don't give them enough. Yet they have your interest to peaked, that you comment frequently on their forum about ME. And plan to buy ME-A. Despite your own criticism, low expectations and chagrin about ME Trilogy endings. I think they have you pegged squarely in their crosshairs. IMO, ME Trilogy was executed intentionally incoherent. But was done so in a very predictable and creative manner. I loved it entirely. And that is why I can't wait to play ME-A on day one of its release.
7. "But I don't give a sh!t about Andromeda. I don't live there. Earth isn't there. Palaven isn't there. Sur'Kesh isn't there. Tuchanka isn't there. What interested me about the future of Mass Effect was how the species would progress and interact technologically, politically and militarily after the Reaper threat had ceased looming over the galaxy."
That's akin to saying I don't give a damn about South America, Canada, Japan, or any other nation because Kansas, California, New York, Boston, Chicago, aren't there. And all that interests me is how "human species" from all the other races from other nations on Earth blend together to create a United States of America. Bioware actually gave you the option to play the ME trilogy from that perspective. You're apparently just dissatisfied with their end scenario for you. Meaning; total xenophobic annihilation by a massive foe which unites through assimilation. Which ironically the USA is supposed to actually be about.
8. "So you are seriously asking us to trust that BioWare ruining the original trilogy was all just a part of their overarching plan for the franchise?"
In a word; No. Your assumption of "us" is much narrower than you perceive IMO. It is simply you and those Bioware is willing to disregard, if you have no interest in the ME Saga going forward. Because neither "they" nor "I" view the original ME Trilogy as ruined in any way.
9. "We have never actually heard BioWare's side of it, besides the oft repeated "We stick by our artistic integrity."
This is in response to a point you made , which was not specifically made to me. But I propose "we" have never heard from them on it. Because of many of the reasons I laid out above. Meaning: they will make their case in future games/trilogies/DLC. And let us go crazy making up our own meanings.