Although Nightwolf is not yet available to be directly purchased in Mortal Kombat 11, many Kombat Pack owners have unlocked the character, downloaded him, and began playing as the Makotan warrior. Many have already figured out some of Nightwolf's best combos and strategies, as well as beating his Tower to unlock his personal character ending. It's worth highlighting that, since we are explaining what Nightwolf's ending means, this article will contain MAJOR SPOILERS.
After defeating Kronika, Nightwolf takes on her role as Keeper of Time, meaning that is is his duty to protect and manage the timelines. He recaps how he, who was originally named Grey Cloud, originally became Nightwolf before admitting that he cannot be Keeper of Time and Nightwolf (a mantle that has been passed down in his tribe). Mortal Kombat 11 version's of Nightwolf then releases his mantle, passing it on to another in the Makotan tribe.
Then, as he fades out, a single image appears teasing the next Nightwolf. It sees a young warrior standing over a body, defending her tribe against those we can only presume would do them harm, with this new Nightwolf set to be a young woman. Because of this, it seems unlikely that Mortal Kombat 11's Nightwolf will return in future entries, but we can likely expect to see a new character, a young Makotan woman, accepting the mantle in Mortal Kombat 12.
Yet the confusion lies in whether or not this is canon. Developer NetherRealm Studios has selectively chosen canon endings in the past, with many fans thinkig that Liu Kang's Tower is the only official ending. Scorpion's, Sub-Zero's, and Sonya Blade's have sort of hinted at the future of the franchise, but it's unclear how much influence that will have. Regardless of canonicity, it doesn't seem NetherRealm would tease a female Nightwolf (which can be seen below courtesy of Gamer's Little Playground) if that didn't come to fruition in Mortal Kombat 12, if not sooner as Mortal Kombat 11 DLC.
It's a small thing in Mortal Kombat 11, but it has huge implications for the future of the character. It seems doubtful that Nightwolf, as we know him, will ever return as a playable character, but it could create a serious dynamic between him if he were to have a cameo and the next Nightwolf, whenever she becomes playable.
Mortal Kombat 11 is out now for PC, PS4, Switch, and Xbox One.