system
Given the following post, respond as if you're commenting on Reddit:
human
[MCU] How different is the world if Bucky fails and Howard Stark isn't killed on Dec 16 1991?

How does this affect Tony? And the avengers as a whole?
gpt
Surprisingly similar.  Bucky follows up with a second attempt and retrieves the SSS, allowing the creation of more Winter Soldiers.  Three and a half years after he would've died, Stark and his wife are killed in a freak airplane accident caused by his partner Obadiah Stane. 

Spurred on by his father, Tony would've finished his graduate studies, but his trajectory is otherwise unaltered.