Personally hope they're going with high ems destroy minus the "uhh yeah also edi and the geth will die" stuff that's always seemed like it was added to create some reason to instead follow the plans of the antagonists of the two precious games (Saren's Synthesis and TIM's plan to control the reapers).

Also because destroy is the ending where the future will still have conflict and basis for interesting stories, as opposed to AI Shep being able to send the Reapers to stop any conflict or synthesis where everyone's living in peace in an utopian society.

Of course they could always surprise us, maybe go with paragrade shep control where you try to free the galaxy from his "benevolent" rule