Avengers: Infinity War - Every Character Ranked By How Likely They Are To Die
15. War Machine

After having his spine broken when Vision accidentally shot him out of the sky in Captain America: Civil War, you'd think War Machine had gone through enough already. Enough, in fact, to retire from Avengers action entirely, but he's clearly not that sort of guy.
With that major trauma already in his recent past, you'd think he'd be safe, but he's very much like Falcon in that he'd be an easy character to kill for effect without too many long-term trade-offs. And his death would certainly have an effect on Tony Stark when he eventually finds out.
War Machine was also literally punched to death by Thanos in the Civil War II comic event, so there's precedent of it not going well for him.
14. Bucky Barnes

There's a school of though that suggests that Bucky Barnes will inherit Captain America's shield when Steve Rogers is retired, but anyone thinking that has missed the fact that he's been publicly implicated in assassinations and probably wouldn't be taken to quite as well by the American people as Rogers was.
That would also require him to survive Infinity War, which is far from assured, given that we see him apparently rushing into battle with Thanos after the Titan has defeated his best friend in individual combat. That's certainly what the emotion of that scene seemed to suggest.
And while there is some poetry to the idea of Bucky getting vengeance for the death of Cap, there's even more to the idea of him following him to death. After all, they never wanted to do anything without each other.