Avengers 4: 11 Things That MUST Happen
4. Gamora & Nebula Double-Team Thanos
Though Captain Marvel needs to be the one to sufficiently weaken Thanos, that doesn't mean she has to deliver the killing blow itself. Two far more poetic candidates for that job would be Gamora and her adoptive sister Nebula (Karen Gillan), what with the historic abuse they've suffered at the hands of their pop, most recently being literally murdered and tortured respectively.
Seeing the two taking on a weakened Thanos and landing the killing strikes would be an enormously cathartic moment for the pair and audiences, and in the event that Gamora actually turns out to be perma-dead, Nebula killing Thanos herself would be loaded with even more dramatic potency.
Sure, there's potential for this to be a little cheesy, but given the Russos' track record, it's easy to have faith they'll do the moment of glorious operatic vengeance total justice.