I think most people get tired of the death cockteasing they keep doing. After Loki "dying" several times throughout the series, bringing Coulson back from the dead for AoS, Pepper in Iron Man 3, Fury in the Winter Soldier (I'll let them off with Bucky because he was always going to be the Winter Soldier), Groot grows back in GotG.

A death fake-out is a fun plot device the first 3 or 4 times you use it, but when it happens almost every single time then it severely lowers the stakes in any engagement. I love Civil War, but the latest death fake-out with Rhodey made me groan.

Having said all that I have my own pet theory that Tony is going to die during Infinity War. It would be the ultimate conclusion to his story arc: self-obsessed narcassist in his first film and after that he begins to consider the welfare of others more and more as the story goes on - by the time we get to Civil War he is battered and bruised and is so much the humanitarian that he is willing to arrest his friends for the safety of others. Anyway, I think that sacrificing himself for the party would be the final step in this evolution - he's already seen the visage of his friend's lifeless forms strewn across the battlefield, I think new Tony would gladly balance that equation by sacrificing himself to stop that from happening. Plus his catchphrase always seems to be "Come on you're killing me!" and there's a scene where he walks past letters painted on the wall and they read "L8". :D