A year doesn't go by when I don't hear someone say "[game] doesn't need multiplayer!" Except, did you ever ask yourself what kind of multiplayer that would be like? The XCOM: Enemy Unknown team asked themselves that, and what resulted is a surprisingly popular turn-based RPG style multiplayer that even got a wealth of new maps in the expansion pack Enemy Within.
The same happened with Mass Effect 3, and later Dragon Age: Inquisition. Perhaps its time we stop saying something shouldn't be done, and start more regularly asking "can this be done, and will it be fun?" Not only does this open the door to new multiplayer games, but it lets mechanics be handled in new ways. Assassin's Creed: Rogue's detection system wouldn't exist without Assassin's Creed: Brotherhood's multiplayer, and similar examples exist across many franchises.
So let's really push the envelope and see what works. If it fails, then go back to the drawing board; but if it succeeds, then help it grow.