"I think there's a novelty to having a downloaded guest character," Boon said at the 3:56:00 mark in this Madcatz-produced video. "The chances of [having] at least one of them will be pretty good."
A Nightmare on Elm Street villain Freddy Krueger previously appeared in 2011's Mortal Kombat as add-on content, and Mortal Kombat's Scorpion went on to guest star in fellow NetherRealm-developed fighter Injustice: Gods Among Us in 2013.
Though classic combatant Raiden recently joined Mortal Kombat X's playable roster, Boon notes that the game will feature "more new MK characters since the first [Mortal Kombat]."
Boon assured that Mortal Kombat X's add-on content could host an array of returning fighters beyond its initial roster, however. "If you don't see your favorite character, there's always the DLC characters," he said. "[You] can hold out hope to see that we're going to include them."