^ Which is one of the reasons a prequel is the most likely choice. If you think about it, the real untold story of Mass Effect is the one they tried to tell in the novelizations: the adventures of John Grissom and David Anderson, the discovery of the Charon Relay, the First Contact War and the occupation of Shanxi, etc. We sometimes forget that those events totally reshaped the way humanity viewed itself and the universe around them... and they happened less than a generation before Mass Effect 1.
You could spend AT LEAST one game exploring those first steps into space, depending on where you started. I could see Bioware letting you start the game as a Privateer, a Merchant, a Mercenary or an Explorer; your opening missions, the kind of ship you're flying and the kind of equipment you can take with you depend entirely on your choice, even if the game ultimately ends with the Council stepping in and telling the Turians to calm the fuck down. I'd also be looking forward to seeing the Batarians actually show up as a primary adversary instead of a bunch of four-eyed canonfodders who don't know any better.
I just realized this, too: in all of Mass Effect, we never did get to see what a Batarian warship looked like, did we?
While I agree a prequel is probably the most likely approach (*if* they're even worried about post-ending complications) I don't agree that centring it in the First Contact War is a suitable setting. For one thing the outcome is already known, so that immediately limits the scope of any story they choose to tell.
On the other hand I *could* see it taking place in the immediate aftermath, just as humanity begin to take their first steps into the galactic community. Maybe the game opens as you playing an ex-military type (because we all know it'll be combat based gameplay) turned colonist. The colony is hit by Batarian slavers and moves on from there.
The prequel idea does have some drawbacks though. For one they're going to have to either go back to weapons that cool down, or find some way around having a reload mechanic without thermal clips. That may seem minor from a story POV, but it's really at the core of the gameplay mechanics and that's not something that can be changed lightly.
Also, while it'll be tempting to have familiar faces show up (young Anderson, Saren, TIM etc.) their involvement and interactions will have to be very limited.
I think that they'll be most likely to choose from whatever is done the most, with destroy being done the most often, it's a likely front runner.
I dunno. Ignoring people who killed Leliana in the first Dragon Age
is one thing - you're locking out a very small number of playthroughs. Locking out up to two-thirds of them? I'll believe it when I see it.
Did they ever release the official numbers on that? All I can recall was that independent survey on some German fan site a few months back. Either way, I doubt the proportion of users who pick anything other than 'destroy' is as high as two thirds. *Maybe* a little over half?
Also, the thing about Dragon Age was that it gave the player a little too much freedom for the whole "import your old save" thing to be 100% practical. In Mass Effect things a much more restricted, which was actually one of the major complaints even back when ME2 was released.
I think given the marginal variance in endings, it might even be possible to accommodate both Control & Destroy. Say for example if after a few centuries, when things had fully stabilised, Shepard's reapers went back into hybernation in dark space to allow organic life to progress on their own. The only practical difference could be a single in-game line that mentions if the reapers are gone for good, or gone for now.
Synthesis just isn't practical.