We know it is going to show up. After the killing of Avalanche for the Axis deaths are likely on the way. Who will Marvel Red Shirt before X leaves for off world. Your 3 guesses and who might be immune or stay 3 guesses.
Culls
1Husk-It would affectCannonball thus Avengers
2High Tide/Loa all Atlantain Mutants-a clenseing to streamline Movie Rights
3random Morlocks - Often victims of culls
Immune might stay on Earth
1X23-healing factor
2Penance-truly indestructible
3Cosmic Angle-cosmic upgrades
Have fun and let us see if we can figure out who Disney/Marvel wants out of the way.