Probably a stable of three, aiming to fill a few specific niches.
1. A high pressure, heavy rushdown character who seems to have a decent chance of being competitive. For this slot, Jax is a contender based on high aesthetic appeal, Sonya based on her gameplay potential, and D'Vorah as a mix of both.
2. A character with balanced offense: good combos, strong space control, some zoning. Also with a decent chance of being competitive. Raiden and Kitana are top contenders for this slot, with Kabal as a dark horse candidate.
3. A character who just feels off-beat and cool, ideally with a lot of different crazy stuff going on. This one's just for fun; doesn't matter if he/she is competitive. Atom filled this niche in Injustice 2. For MK11, it will probably be Cetrion but Kollector will get a close look too.