Longtime comic book readers know that death is rarely permanent in superhero worlds. Heroes and villains die all the time, but most of them usually return, be it though mystical/science-fiction resurrection, reality re-writes, their deaths having been faked, etc. However, when it comes to superhero cinematic universes, the death rules are more strict than they are the printed page, so if someone bites the dust, it's more likely to stick. That's now confirmed once and for all to be the case for Brock Rumlow, a.k.a. Crossbones, who exited explosively last year in Captain America: Civil War.
If DeMonaco was still involved and they came up with a great idea, then I think I would do [another Purge movie]. Otherwise, I think I'm done. Same thing with Captain America. There's nowhere for it to go, unless you're Captain America or Iron Man. They were talking about it, but I was like, 'You know what? I'd just rather not do it.' ... It's time to move on. Don't stay at the party too long, or you get knocked through the ropes.
The last time moviegoers saw Crossbones on the big screen, he had detonated his explosive vest to try to take out Captain America along with him. Scarlet Witch managed to lift the mercenary into the air and keep the explosion away from Steve Rogers and the citizens on the ground, but the blast took out a building nearby, killing many inside, including several Wakandan citizens. This event was the final push to convince the world's governments to enact legislation regulating enhanced beings, thus kicking off Captain America: Civil War's main conflict.
Being caught in the middle of an explosion is about a direct way to go out as possible, even more so than having a building fall on you in Captain America: The Winter Soldier. That said, there's still a slim chance that Crossbones could have been included in a future Marvel movie. After all, with Thanos coming soon with the power of the six Infinity Stones at his disposal, maybe he could have been resurrected. Or, as a simpler solution, he could have been seen in a flashback. However, Frank Grillo made it clear that he doesn't want to return to the MCU, as there's nothing else meaningful for him to do in this franchise, and he's ready to exit "the party." So for those of you who were nursing a glimmer of hope for more Crossbones in the continuously growing MCU, extinguish it now.
Although Crossbones is out of the picture for good, his nemesis, Captain America, will return alongside almost every other Marvel hero when Avengers: Infinity War is released on May 4, 2018.