Combo Breaker is going down this weekend, from the 25th to the 27th of May,and it quite possible MK11 teaser trailer revealed read below for more details
The details of the leak, which also includes details of Lego Incredibles and DC Villains, if you're that way inclined (though if so you're almost certainly too young to be on this website) can be found here. As you can see, the original source for the leak is the ever-reputable 4chan but, that and the natural high levels of salt such leaks should be taken with, it would seem fairly plausible.