Endgame for a Title is perfection. The Music, and talking between the Avengers trying to figure what to do next against Thanos, while not showing any Action in that plan was so well done. The pain of alot of these Avengers isn't finished, man this is going to break me into a Million pieces and I might be able to be put back together again.
My opinion may be in the minority here but my biggest <img src="http://i.imgur.com/GkHkVKq.gif?1" border="0" alt="" title="" class="inlineimg" /> moment was Scott Lang showing up at the end. Given that this will probably be the final movie for some of the OG Avengers, I LOVE that Ant-Man is going to play a significant role in this film. Considering how many of the newer people got dusted, I really think they picked the right one to still be around. And, if you think about it, his appearance was really the only thing plot related that they even showed us in this teaser. All of the rest is stuff we mostly already knew. Tony is trapped in space. The Avengers were defeated. Thanos did what he said we would do. Clint's appearance is only a minor spoiler. But Scott Lang still being alive is most definitely plot related.
The one who was really notable to me in his absence was Rocket. I'm rather hoping to see him get a decent amount of interaction with the Avengers in this movie.
I think probably the biggest question raised is who will be the one to rescue Tony? My money is on Captain Marvel picking him up on her way to Earth to answer Fury's page. I'm open to a better suggestion but the only other people I can think of who might be out in space right now are Valkyrie and Korg with the surviving Asgardians and I'm not really expecting them to be in this movie.
My bets are on either rocket racoon, Ms marvel or yeah the surviving asgardians I guess. Neubla probs ditched him so can't see it being her