Invade mephistos realm and rescue cyclops soul like thunderbolts did with hellcat.
Alternatively have Wanda say no more deadclops
Have mephisto visit jean and Scott in afterlife where they are enjoying married bliss and make him offer to bring cyclops and jean both alive if they offer him their marriage.
Have eternity and the first firmament visit earth firmly declaring CYCLOPS WAS RIGHT and he is going to be revived to become the newest living tribunal ala hal Jordan after the eternity war.
Have death resurrect him to correct a grave cosmic balance caused by the proliferation of inhumans as her avatar to slaughter them with his body terrigen odours.
have jubilee time travel and give him a bite when he has just died but his soul has not yet ascended which will make him come back as a vampire mutant zombie walking terrigen plague weapon which will immediately be appropriated by weapon x.
Just tell him wolverine is coming back through again making a deal with the angel of death cuz he got a update that jean was coming back and wanted to be back first so he will have a clear playing field.
the mutant Threnody could bring him back
I suppose given what happened in Captain America 5 Selene is a definite option.
Also the infinity stones
I think they'll say Scott never actually died. Emma put him in a comma or statis chamber at the last minute, and then all they have to do is introduce a cure and have him wake up. It seems like the easiest way to bring him back.
One option to allow for resurrection, while not making it 'too easy' or easily replicated on everyone that dies would be to use a traditional mutant healer like Triage or Elixir (or both working together) combined with one or more mutant-power-enhancing / replicating peeps like Mimic, Rogue, Chance (from Fallen Angels series), Fabian Cortez, etc. Without the massive power-up, it could be argued that the healer can't normally resurrect people (especially those who have been dead awhile, or whose bodies have been messily burned up or whatever, to keep it from being the instant solution whenever someone dies), and the 'power-booster' like Chance or 'power multiplier' like the Mimic goes back off-stage to eliminate the temptation to trot out this power-combo willy-nilly.
OTOH, I feel like any resurrection taking place at the hands of a villainous sort like Sinister or Dark Beast (perhaps being manipulated behind the scenes by Emma?), and the revived Scott temporarily kicking ass as a villain, would be more of a traditional storyline. Even a clone created by one of these villains, finally beaten and then used as a host body for the mind of the real Scott, downloaded from Emma (who has been keeping him 'alive' in her mind) could work, since his character is more important than his original flesh and blood, IMO.
Main problem with evil Cyclops clone is that Lemire already made a bad version of that, so it would feel like retreading.
Also, Triage would really need a boost, since he can resurrect dead people, even if their body is mangled, but the flesh stays like it was and the individual's brain functions aren't all they should be.
Virgins sacrifice.