Avengers: Age Of Ultron - 15 Theories That Were Utter Bull
2. Captain America Would Die
The Theory: Somehow, Ultron would use his new vibranium body to break through Cap's shield and kill him. He would then be revived - possibly using the Time Stone or the Soul Stone or using Vision's Jesus-like powers - in time for Civil War to kill him again.
The Evidence: The trailer shot of Cap's broken shield was pretty firm evidence for some.
The Reality: 'Twas nothing but a hallucination in Tony Stark's mind. His PTSD combined with guilt that he wouldn't always be able to protect the Avengers (despite several of them being basically immortal) to manifest as the immediately iconic shot of Cap's smashed shield.
Would It Have Been Better? No. Not in a million years. The idea that Stark's fear and arrogance would mix to convince him that he alone had the power to save the world was a great nod to exactly how Iron Man's brain really works.