Rather large massive extremely huge spoilers for the Avengers: Age of Ultron are below. Seriously, don't read this unless you've seen it. (I mean go watch it and come back to read this.. now... go.)
The Avengers: Age of Ultron, was possibly the greatest film of all time. Joss Whedon has really outdone himself here, partly because he focused so much on the actual story, instead of world building the MCU for phase 3. But, he has still left us with plenty of new characters (and a new team) whose future needs serious discussion.
I know you're thinking "What future does he have? Isn't he dead?" Well... yes. But it's quite possible that this won't last. Let's face it, in comic books, does it ever really last? Nobody has really died in the MCU to test this theory (except Agent Coulsen, who came back). Rumours are that Aaron Taylor-Johnson signed a multiple picture deal with Marvel, so it is possible we will see him again. Especially since Joss Whedon gave an interview where he talked about how killing people didn't have the same effect if they came back, but that it wasn't his decision to make. This hints at a bitterness towards Marvel, and their possible decision to bring Quicksilver back?? Just a thought, but let's face it, he's much too fun to keep dead.
Dear Wanda has thrown her lot in with the new Avengers team, this pretty much ensures her future as a full time Avenger, involved from Civil war all the way through to Infinity War (where her high power level is sure to help). Looks to me like she will join up with Captain America's side in Civil War, as she hates Tony Stark's guts. Personally, if she is to get screen time outside of Avengers films, I think it is most likely to be in Dr Strange or Inhumans. Dr Strange isn't going to have an origin story apparently, so it is possible that he will become involved with the Avengers through Scarlet Witch, who could take on a sidekick type role to him. Inhumans is where most people see Wanda and Pietro (if he makes a return) but I doubt it as the Inhumans on Agents of SHIELD right now seem to be very protective against anyone who didn't get their powers from Terrigen crystals. Since the twins got their powers from an infinity stone instead, it is possible that they won't be welcomed.
Wow. Just wow. We thought Scarlet Witch and Quicksilver would bring some incredible powers into this film, but Vision was something else. He is truly an Avenger who can fight Thanos, which we haven't seen many of. Albeit, he will come into conflict with Thanos due to his possession of the mind gem. Thor talked at the end of the film about trusting the Vision with the stone, which means to me that the Vision can live without it. However, if Thanos can get the stone off of him, we can assume he won't be partial to letting him go afterwards. This could mean trouble for my new favourite avenger.
The New Team!!!!!!!!!!!!!!!!!!!
This was an amazing way to end the film, and I think, an amazing way to set up Civil War. This team of Avengers includes Tony Stark's best friend, and his creation. No way do they side with Captain America when things get rough, so that will be a big part of the film. Also, let us not forget that this definitely removes any possibility of Thor or Hulk taking part in the war. It seems like we will be seeing a couple of new teams after the third Cap film.