Disney Infinity 3.0 is set to com out later this year, with the big addition of Star Wars. Tron characters are also set to appear, with other Disney characters like Mickey, Minnie, Mulan, and others set to join the already massive cast of characters. More Marvel characters are set to join as well, with the confirmation of an Avengers Age of Ultron Playset. This indicates that possibly new versions of the Avengers with their updated costumes will be added, as well as more characters. Hulk buster will reportedly appear. I saw somewhere that it will simply be a power disc that gives Iron man the much larger suit, but I don;t know of that is true. Also, I suspect that Quicksilver and Scarlet Wicth will be added. The Vision should be added as well. Obviously Ultron will because he is the main villain, and all other marvel playsets include the villains as a playable character.
Here are a few other Marvel character that I think should be added, besides Quicksilver, Scarlet Witch, Vision, and Ultron:
1) War Machine
4) Jessica Jones
5) Black Panther