Ed Boon received a Tweet asking about what he would think about a Killer Instinct crossover and he responded that he would be for the idea, but it would be a Xbox exclusive. Phil Spencer of Microsoft responded to the tweet saying that he loves the idea. While NetherRealm’s Mortal Kombat series is multi-platform, Killer Instinct is exclusive to the Microsoft brand.
Keep in mind these tweets don’t confirm anything, just that the two aren’t necessarily against the idea. You can check out the tweets below.