Mass Effect 4 is almost certainly making Mass Effect 3's Destroy Ending canon in order to continue the story of key characters like Liara and, if the piece of N7 armor seen in the trailer is anything to go by, Commander Shepard themself. Although making a canonical choice about the ending of an RPG story would be extremely controversial for most series, the controversy surrounding the ending options of Mass Effect 3 when it first released may actually be to BioWare's benefit for the first time.
What could be very controversial, however, is if BioWare makes one of the original trilogy romances canon. In fact, addressing the original trilogy romances will likely have a huge impact on the way Mass Effect 4 has to handle its canonization of certain choices and could have implications for which kinds of choices carry over from the first three games and which do not.
Mass Effect 3's Ending
Mass Effect 3's original ending was widely panned by fans of the franchise. After five years of a trilogy marketed as a choice-focused story where player decisions would have wide-ranging consequences for the galaxy, there were a few massive problems with the execution of the final choice. At the end of Mass Effect 3, Shepard is given the option to choose between three endings—Control, Synthesis, and Destroy. Control involves Shepard transcending to become an AI and taking over the Reapers. Synthesis sees all organic and synthetic life merge. Destroy wipes out the Reapers, the Mass Relays, and in theory all synthetic life in the Milky Way.
There were almost no other decisions made throughout the original trilogy which impacted how this final decision played out. Instead, the final choice was completely isolated. Two players who had made the exact opposite decisions throughout the trilogy were faced with the same basic options and would see the same final cutscene if they chose the same option at the end. Originally, the three cutscenes were also nearly identical except for the color of light dispersed from the Crucible across the Milky Way—blue, green, or red.
BioWare released an extended cut that added some extra details to differentiate each cutscene, but by and large, the damage was already done and most Mass Effect fans reconciled themselves with loving the series in spite of its ending. Fortunately, the isolation of the final choice made ignoring the ending easier. Ironically, the lack of attachment to Mass Effect 3's ending may now help BioWare by making Mass Effect 4's premise more palatable to a lot of fans.
Journey Over Destination
Mass Effect 4 appears to be using the Destroy Ending as the foundation for its new story. BioWare has released Twitter images of Mass Relays being rebuilt, the next game's trailer shows Liara walking over a dead Reaper, and by implying Shepard's survival the trailer calls back to the only hint at Shepard surviving the original trilogy—a high EMS Destroy Ending. Ignoring the ending might have been controversial if the original Mass Effect 3 ending wasn't already so widely disliked.
For nearly a decade Mass Effect fans have come to terms with the fact that the original trilogy is a great journey with a dull destination, a dynamic that formed the foundation in BioWare's other reconciliatory DLC, light-hearted companion-focused side-quest Citadel. Most players are likely more attached to their companions, the Normandy, and memorable secondary characters than they are the ending they chose. Many will just be happy at the possibility of playing Shepard again, and designating the Destroy Ending as Shepard's canonical choice is broadly irrelevant to the parts of the trilogy most fans have the greatest personal attachment to.
The canonization of the Destroy Ending makes sense from BioWare's perspective. It allows the studio to build a new galaxy based on the fallout of that decision, one where the members of a star-spanning galactic community were suddenly cut off from one another with the destruction of the Mass Relays and were forced to rebuild. Dealing with the vastly different implications of the Control or Synthesis choices would make telling a new story nearly impossible without some very flexible world-building. However, when it comes to the series' most personal choices—particularly romance—flexibility will be key.
Canonization In Mass Effect 4
BioWare's decision to make some parts of the original trilogy canon raises questions about other world states which will likely be canonized. These include some key decisions that have big implications for the rest of the galaxy like the fate of the Geth and the curing of the Krogan genophage. BioWare can likely get away with canonizing some of these choices—most players were invested in these decisions because of their implications for beloved characters like Tali, Legion, and Mordin, not the galaxy at large. What BioWare is extremely unlikely to get away with, however, is canonizing Shepard's original trilogy romance option.
Mass Effect's romances have a huge impact on each playthrough, and ultimately end up some of the biggest differences between playthroughs next to Paragon or Renegade alignment. Picking one romance would be extremely divisive. It would be so divisive, in fact, that BioWare is extremely unlikely to canonize a romance choice if Shepard is the player character again.
This makes it likely that despite the canonization of the Destroy Ending, Mass Effect 4 will import some of the player's decisions from the original trilogy, or at least have them fill in some answers about the original trilogy before starting the game. This could make Mass Effect 4 a strange hybrid, with some parts of the original trilogy canonized while others are taken from player decisions.
BioWare will have to be careful to strike the right balance. Players may be willing to dismiss the original trilogy's destination, but establishing a canon romance choice would massively undermine the journey that kept Mass Effect a beloved series despite the third game stumbling at the last hurdle. Dealing with romances in Mass Effect 4 could be a huge challenge in and of itself, with players hoping to reunite with their romance option. The extent of the challenge will depend on whether or not Shepard returns as the player character, but after the hints in the Mass Effect 4 trailer, Shepard not returning could be its own controversy. After Mass Effect 3, however, if there's one thing the series has experience with, it's controversy.
Mass Effect 4Â is in development.