If you try to pair fighting games, Tekken and Street Fighter go quite well together, and this has lead to crossovers in the past. For Mortal Kombat, the best pairing would definitely have to be Killer Instinct. Both games offer a slightly more brutal approach to fighting, and according to Ed Boon, the idea of a Killer Instinct and Mortal Kombat crossover would be a good idea.
On Twitter, Ed Boon mentioned 'I loves me some KI but a crossover would have to be Xbox exclusive.'
Funnily enough, Phil Spencer later tweeted in reply to state that he 'loves' the idea too. Well, right there we have the two men that could make a real crossover happen, and they both agree on the idea.
Whether or not this was a little marketing ploy by both Netherrealm and Xbox is hard to say, but we wouldn't be surprised if a Killer Instinct and Mortal Kombat crossover title was now in the works. Because Killer Instinct is Xbox exclusive, the crossover would also have to be Xbox exclusive, which is a bit of a shame because Mortal Kombat has always been available on multiple platforms.
With that being said, with Xbox's recent adoption of Windows 10, it's likely that a future crossover would also be available on Windows 10 PCs. Unfortunately we doubt we'd ever see the game reach PlayStation and that's if it ever did come to light at all anyway.