In case you somehow missed it, a new Injustice animated movie was announced, and as a result, Injustice 3 speculation has erupted all over the internet -- in part thanks to Ed Boon, the creative director of not just Mortal Kombat, but the Injustice video game series. As you would expect, the movie announcement blew up, and "Injustice" has been trending on Twitter ever since. Boon hasn't commented on any of this speculation, but he did add fuel to the fire by screenshotting the trend and tweeting about it with no further context.
Now, some have taken this as a soft confirmation that a third game is in the works. While this is possible -- if not probable -- making this conclusion based on the tweet is certainly a stretch, especially considering Boon does occasionally indulge in some trolling and misdirection.
That said, Boon's tweet isn't the only thing contributing to the speculation. In fact, most of the speculation is purely based on the announcement of the movie, which comes during a window of silence about what NetherRealm Studios is working on. After releasing Mortal Kombat 11 in 2019, many expected to see Injustice 3 this spring. Obviously, this didn't happen. Not only has the game not been released, but it hasn't even been announced.
Of course, an Injustice animated movie being in the works doesn't mean Injustice 3 is in the works. Alternatively, it also doesn't rule out a third game being in development either, as the movie will probably exist in a completely separate universe. However, you'd assume WB would want to get some synergy going and get the third game out around the release of whatever this new animated movie is.
Back in April, a rumor surfaced claiming that NRS was working on a new Marvel game. At the time, this generated a lot of buzz, but this new announcement does cast a little bit of doubt on the claim.