*spoiler* If you haven't seen Age of Ultron then you might want to skip this, but this isn't spoiler intensive, so you'll probably be good regardless*
So, who do you think is going to be the next Avengers line-up for
Avengers 3? Captain America IS the Avengers, so he's gonna be there, and they're never going to let Robert Downey Jr. go if they can help it, so Iron Man will be there, and Thor is the third cash cow of the MCU, so in all likelihood he will be there as well.
So, Captain America, Iron Man, and Thor are almost a lock, depending on contract ****.
But they've already kind of jettisoned the Hulk, who was already an also-ran character in the movies, so I suspect that if he's even in the next movie, he will have only a bit part. As much as I love Hawkeye for his recent comic book series, as far as the MCU goes, he's even more of an irrelevance, so he's probably out. Black Widow may very well be out as well, even if she's being played by Scarlett Johansson. After the insinuation at the end of
Age of Ultron that the Avengers are going to have a lineup change, these three seem to be the easiest to ditch, so I'm predicting that they are gone.
As for who will be taking their place, they made too much of a fuss over Vision to simply pretend that he wasn't a thing, so he's in as far as I'm concerned, and they're not going to include Vision without Scarlet Witch (god I hope they get a different actress to play her). So those two are probably a lock. And if Scarlet Witch is going to be in the movie, then it would be odd if Quicksilver dropped off the face of the Earth, so he's probably going to be there too (again, I seriously hope they get a better actor for him).
I kind of suspect that even though Falcon showed up at the end of
Age of Ultron that Marvel isn't going to be too concerned with including him, so he's by no means a foregone conclusion. I hear
Ant-Man was good (just downloaded it, so I'll know soon enough) but it didn't seem to have made enough of a splash to warrant his inclusion, as he would basically be a new character who just so happened to have his own movie. (And would he really be that interesting without the first Ant-Man's relationship with Wasp, which Marvel would never dream of including in a PG-13 movie). But I would still love, love, love to see Paul Rudd in a Joss Whedon movie, so even without having seen
Ant-Man, I am hopeful.
As far as "new" characters go, I'm officially predicting Spider-Man. With Marvel and Sony's new deal, there's no way that Marvel would waste his inclusion in a Marvel movie on anything less than an Avengers movie. Related to Spider-Man, my ultimate dream would be for a version of the
New Avengers, which might be slightly possible with the success of Daredevil (though I haven't gotten far enough in
New Avengers to know if he actually joined the team), and if the Luke Cage show succeeds then he might be viable, but I'm not really expecting much. The very fact that "Spider-Woman" sounds like "Spider-Man" probably means that she will never be in a Marvel movie (though her appearances in
New Avengers,
Spider-Woman: Agent of Sword, and her most recent solo series makes me hopeful, as Jessica Drew/Spider-Woman is awesome). And it would mean the moving of hell and earth to get Fox to agree to put Wolverine into a Marvel movie, so that's probably not happening.
But seriously, how awesome would an Avengers movie with Captain America, Iron Man, Spider-Man, and Wolverine be, regardless of who else was in it? If it were possible then Marvel would do it no matter what characters they had to give the shaft to. Hugh Jackman in an
Avengers movie would pretty much double the ticket sales all by himself.