4. No Other Playable Races
Something that came from the Comicon unveiling was a smattering of concept art pieces alongside the confirmation that the hero of ME4 would be human - at least for now, the aforementioned notion of nothing being set in stone holds true. If this is true it's a blow to those theorists that really wanted Bioware to carry through what they started with ME3's race-based multiplayer, the idea being to let you play as a variety of aliens across a dedicated campaign. It'd be a massive undertaking for the team to not only create an explorable galaxy alongside a fantastically in-depth narrative, but to also pepper it with enough branching paths that would rely on the races themselves through dialogue choices or actions - although if anyone can do it, it's Bioware. With the Turians, Drell and Quarians being three examples that are close to humans in their physicality, it wouldn't be too big a leap gameplay-wise to let you embody them through the new story, but we'll have to wait until more official materials are released to see if any of this is true. There's every possibility you could switch between your squad, Dragon Age-style.