Steve has been Mr. Self Sacrifice from the off; so that's not his arc. His arc is finding his place in the world. He tried the Army, SHIELD, the Avengers before finally being ready to settle down and getting the happy ending he always deserved. And it's not like it was an inability or anything, it was an unwillingness to truly engage with the world he'd dedicated his life to.
It's not a coincidence that the calls for Steve to "get himself a life" got louder and louder.
More than anything else, Stark had to learn the meaning of sacrifice from Steve, as it was not a natural trait in Stark at all.
Not sure about that he specifically needed Steve for that, his whole arc since IM went in that direction before ever meeting Steve. I'd say Tony would have flown that nuke into the wormhole even without that whole "lying down on the wire"-speech. IMO Tony's being willing to sacrifice himself in Endgame wasn't so different than back in Avengers - then and now, it was the only way, and he never shirked away from what was needed to be done.
And I'm not even factoring a "sacrifice of the 2nd chance at happiness" (see below) in here because in that situation he knew, he had to take up the gauntlet to save everyone else, incl Morgan. There was no real choice between living in happiness and death (for everyone). I think that choice was made way earlier when he decided to go back to the Compound with the working time-anchor (and recorded the farewell-message). But as Pepper said, even that moment was built up to by all the previous movies.
I'd rather turn the tables: Steve had to learn the meaning of living for something (beyond being "a laboratory experiment"), of putting his own happiness at least on equal standing, of having something worth sacrificing everything for - and Tony showed him that. Actually, I'm not so sure the two characters are so dissimilar in that regard (and the guilt complexes that have guilt complexes of their own). Granted, they come from contrary points in life, but both their arcs involved finding meaning and purpose in their lives.
I still hope we'll eventually learn what Steve did in the past and whether he created a different timeline by going back or whether he went back to "ours" and just spent his life hiding (which would contradict everything we know about him, leaving Bucky to suffer at Hydra's hands etc). I like to imagine Steve and Peggy, a rescued Bucky, and Howard Stark (incl his eventual family) and Jarvis (and his wife) to be live happily ever after, Hydra destroyed etc. *g* Maybe the Bucky and Sam-series will shed some light, dropping some soundbites.
Agreed. I would've been disappointed if Tony's arc ended with retirement/mentorship because that leaves the door open for easily returning to the status quo. Tony was so very desperate to protect the world and that was clear since his solo movies, let alone the Avenger movies. He had to die. Like Reverend said, not only did he have to sacrifice his life, he had to sacrifice the second chance at happiness with his family.
And I think that's why they made it quite clear with Tony that he was actually dead. We saw him die, we saw the arc reactor go dark (which wasn't even connected to his body/heart's function by that time - but still powerful imagery driving the point home). I have to admit that I actually grieved, granted, it's a fictional character, but even knowing it would be RDJ's last MCU movie (and at the latest, from the moment Morgan appeared on the screen, it was obvious they were going to go down that road), the reaction was still real.
So, bringing Tony back via the multiverse would cheapen the effect of Endgame, even bringing him back as AI... for whom? The only characters with AI-support are right now Rhodey and Peter... I don't see a Rhodey movie on the horizon (too much of a side-kick), and Peter has to learn to stand on his own feet. Negating his grief by way of an AI that Tony just conveniently worked on would be cheating.
