When BioWare first revealed the new Mass Effect during The Game Awards in December 2020, fans went wild for the idea of seeing the series make a return to form with fan favorite characters and the Milky Way galaxy. While BioWare has suggested that both galaxies from Mass Effect might be making an appearance in the new game, the overarching narrative of this game looks like it could be taking place after the legacy of Commander Shepard.
Of course, with the idea that the series will be returning to the Milky Way, many players are excited for the next Mass Effect to involve Commander Shepard in some way. However, whether this return of the old protagonist is as a playable character or a cameo like Hawke from Dragon Age: Inquisition, it might not actually be what's best for the series as a whole.
Undermining the Original Trilogy
The temptation to take Commander Shepard out for another adventure is definitely there for most fans of the series, especially those who were disappointed by the state of the Mass Effect: Andromeda launch. So, when it comes to creating a new game that could appeal to the widest audience of fans possible, bringing Shepard back alongside Ryder might be a compelling option. That being said, deciding to revive the original protagonist runs the risk of completely undermining the character's sacrifice made at the end of Mass Effect 3 to stop the Reaper Invasion.
This of course leads to the critical response of Mass Effect 3's ending, namely that fact that it had been almost universally panned by fans for having done far too little to account for every decision the player had made up until that point. Reassessing that might be an issue worth addressing in Mass Effect: Legendary Edition, but Commander Shepard's sacrifice isn't the type of thing that should be retroactively removed in a future title. The overall execution of the ending may have fallen short for some fans, but walking a Shepard that players had grown attached to over the course of three games to their death did still maintain a significant impact.
Failing to Give Ryder a Fair Chance
Aside from undermining the death of Shepard, bringing the character back before fully exploring the narrative that Ryder had already begun would be cheating out another quality protagonist of their real chance to shine. For one, Mass Effect: Andromeda's positive Steam release shows that the game underneath all of the bugs and glitches was a worthy addition to the series, but the game being rushed out in a broken state applied a stigma. So, there really is no reason to give up on the Pathfinder now, as long as BioWare can focus together to deliver on the type of game that the developer has done time and again already.
In the case of why fans are so attached to Commander Shepard in the first place, the character didn't really come out into their own until their second outing in Mass Effect 2. Shepard's bad dancing, the majority of their romance options throughout Mass Effect, and the subtler ways they interact with the crew really didn't develop until the sequel. So, cutting Ryder off before BioWare can really flex the character in the way Shepard was allowed to would be doing a real disservice to what had already been established in Andromeda.
Convoluting the Timeline or Trivializing Death
There are only two options for how to bring Commander Shepard in line with the current timeline of Mass Effect: Andromeda in the way BioWare has been hinting at. Either Shepard never died and decided to immediately enter stasis and wait for the effects of the upcoming title, or another Project Lazarus brings the character back to life the way it had in Mass Effect 2. Unfortunately, both of these options make way for either a strange situation where somehow Shepard's leadership wasn't needed for 600 years and they were fine with sitting by while the world went on around them, or death has no meaning.
It's the trivialization of death that might make the biggest impact on the Mass Effect series, with someone who had been utterly destroyed in the ways that Shepard had just popping back into place. This is the kind of thing that opens up dozens of plot holes and minimizes the impact of what should be powerful character moments where the player has to choose who lives and who dies. The toughest choices in Mass Effect would now equate to Commander Shepard putting people they don't like on ice, since it's apparently possible to bring people like the original council back from complete obliteration.
Giving up on Mass Effect: Andromeda
This is a problem with the entire idea of the new Mass Effect abandoning Andromeda, with the start of a storyline being left behind in order to relive some of the older hits. Moving back to the Milky Way, where things are more familiar to the original trilogy fans, means backpedaling on the stakes that were raised during the 600 year journey to Andromeda. Now, it isn't a matter of whether or not Ryder and the other Pathfinders are able to make a new home for whoever survived the trip, but simply hold out long enough for reinforcements to arrive.
It might be true that Ryder doesn't know that the ticking clock isn't actually there and that backup is on the way to help create a foothold in a brand new galaxy, but that really doesn't matter. From a narrative perspective, once the player knows that it isn't actually do or die, there's suddenly less incentive to do, since the backup can replenish whatever had been lost to Mass Effect: Andromeda's new alien enemies or the Scourge. Connecting these two arms of the franchise will take some surgical precision to make sure that nothing is lost in the transition from the new back to the familiar.
Milking the Milky Way
Finally, there is the issue of staying in the Milky Way now that the Reaper Invasion has been finished and Cerberus has been otherwise dismantled after the death of the Illusive Man. Aside from reorganizing the galactic government, or shipping off to Omega to put down a random mob boss, there's nothing left to do in the Milky Way that can compete with the events of the original Mass Effect trilogy. All of the new, interesting mysteries to uncover are now off in a faraway galaxy, and Ryder is already there discovering alien technologies and fighting new enemies.
The only thing that Commander Shepard can do at this point is continue to leech off of the original series in order to maximize on nostalgia. It would be a misguided effort that BioWare has proven to be able to move past with the Dragon Age series that trades off new heroes after every game. When all is said and done, there just isn't any room in Andromeda for Commander Shepard, so the only reason to bring them back would be to copy the Mass Effect: Legendary Edition and milk the nostalgia of the original trilogy for all it's worth.
A new Mass Effect is currently in development by BioWare.