Elizabeth Olsen's Scarlet Witch is expected to return from the dead, if only because her contract runs into Phase Four, and due to her romance with Paul Bettany's Vision, many anticipate the android will return as well for to give the couple a happy ending. However, unlike Wanda, Vision was killed before Thanos' snap, when The Mad Titan plucked the Mind Stone from his forehead. To go and undo this might feel like the directors are crossing that line they try to toe.
Keeping Vision dead would work better for Wanda's evolution since, so far, she's always had males around her as emotional crutches -- first, her brother Quicksilver, and then Vision. We need to see her breaking out on her own, and with the PTSD she's sure to endure through all these tragedies, we just might move closer to getting that unhinged Scarlet Witch that's been quite the power-player in the comics.
As Asgard's sentry, Idris Elba's Heimdall hasn't really made waves in the MCU, apart from fleeting moments of fighting off Malekith's minions in Thor: The Dark World and hiding refugees away from Hela's wrath. Other than that, he's been a supporting player, so Thanos killing him made sense. Losing his best friend in front his eyes motivated Thor and definitely matured him as protector of the Nine Realms.
In other words, ensuring Heimdall remains dead advances Thor's journey from prince to battle-hardened king. With Thor's new ax, Stormbreaker, now channeling the Bifrost, the Asgardians no longer need the all-seeing warrior in order to traverse the universe. Heimdall's absence also creates a sense a vulnerability and intrigue for the new kingdom Thor has to lead, which will surely be attracting swaths of enemies when it's eventually rebuilt.
The Black Order
One of the few disappointments in Infinity War involved the Black Order's roles in the film. They looked mean and intimidating, but sadly, with their limited screen time, they ended up coming off like underdeveloped henchmen. Only Ebony Maw had a real sense of personality due to his dynamic with Iron Man and Doctor Strange, with the rest being pretty forgettable.
It's no surprise then that when they died, there was no true emotional response from audiences, apart from cheers for the heroes -- which means that no one's really interested in such villains coming back from the dead. There's no need for them to come back, especially since we've seen how ineffective they are when compared to their master. And with Thanos and his Gauntlet already looming over the MCU, there's no need for Avengers 4 to muddy the waters with the Black Order's glowering presence..
Directed by Joe and Anthony Russo, Avengers: Infinity War stars Robert Downey Jr., Chris Evans, Chris Hemsworth, Mark Ruffalo, Jeremy Renner, Scarlett Johansson, Anthony Mackie, Paul Rudd, Elizabeth Olsen, Tom Holland, Benedict Cumberbatch, Chadwick Boseman, Chris Pratt, Zoe Saldana, Dave Bautista, Bradley Cooper, Vin Diesel, Tom Hiddleston, and Josh Brolin. The film is in theaters now.