Okay have to admit, I have not read everything up to this, as I just got back from the movie and wanted it to be fresh in my mind.
First - incredible movie. Just incredible. I NEVER go to movies in first week, nor even first month. I prefer to wait and let crowds thin down. But as I saw more and more posted here, I had to see it before I learned too much. So we went early this morning with my youngest son 16.
Second - some things I noticed....
1) Hulk has performance issues - he has never lost, go back and look, at least in the movies he has NOT lost a battle. Even though he was about to in Ragnarok.
Hulk is forcing no change, not Banner, and I think its because he can't face the fact he was defeated.
2) The REAL power in this Avengers team is Scarlet Witch - and they are playing that up. Per Vision - "You are the only one strong enough to destroy the infinity Stone." - During the battle she turned the tide twice. They are pushing her and it is nice to see.
3) Avengers 4 - will be time travel. The ONLY Avengers still alive - are the originals from the first movie - Thor, Cap, Iron Man, Black Widow, Hulk and Hawk eye.
4) Pictures of studio shots for Avengers 4 show most of the stars in original costuming - again Time travel.
5) Tony Stark is one of the keys. We know this cause Dr. Strange told Tony he saw only ONE scenario where they win over Thanos, Dr. Strange purposely saved Tony, and made sure Thanos got the Time stone. - for sure now that tells me time travel of some kind back.
6) Star Lord is human, after the last movie where he was part eternal - he showed his total humanity in this movie, the struggle to kill and fail on Gamora, and his rage of loss when he heard she was dead. - this too will be key I think.
7) I firmly believe any one that faded into ash will be back after next movie, but I wonder if those who were killed to get there will come back.
As called out by some others at WDWMagic.com - not sure here - I loved the interaction between Tony Snark(not a typo
) and Dr. Strange. As much as I loved the Dr. Strange character so far, he was really at ease and even MORE enjoyable in this.
Loved his snark shot at DC when he asked Tony if Peter was his ward
Those are the keys to me. As I said we went early so theater was not full, but you could feel all the emotion as folks died, or as jokes were cracked.