NetherRealm studios held the 4th Mortal Kombat X and confirmed that Brutalities will be returning. Brutalities will indeed be a bit different than what we had in the past. In previous games, you had to enter in a long combo to pull one off.
The NetherRealm team didn't reveal exactly how to pull one off but they did say that certain conditions had to be met. They also said that some Brutalities would be harder to perform than other. In this game, it seems that Brutalities act as mini Fatalities that can end a round at the end of a combo. For instance, Cassie Cage has an MMA tackle move where she ground and pounds her opponent. In the Brutality, she performed the same move, but kept punching the opponent until their head split wide open.
In any case, we should have plenty of time to figure them out as they did confirm that there are over 100 Brutalities in the game.
To see Brutalities in action, be sure to check out the MKast stream on either their official Twitch stream or on Youtube.