I don't think it would be a good idea if everybody dies, like who would they show in the future scenes fighting against the Sentinels. A couple of deaths could be moving and powerful but killing everyone except for Wolverine would be too much IMO.
maybe they wont do it ever
I think that Storm is the MOST LIKELY to die, but she'll get a heroic death. I could see older Xavier or Magneto dying. I think that one of them WILL die. I could also potentially see Iceman or Colossus dying. And then some of the new X-Men being introduced are clearly just there to die and show how bad the threat is.
^ no, just lots of hoping
Future Magneto dying while trying to protect his friend Charles Xavier.
Wolverine,Xavier and Magneto are the three most important characters.Wolverine is too iconic so I wouldn't want him to be killed.Xavier already "died" so the death wouldn't have so much impact.Magneto would be the right choice.