Avengers: Infinity War - Predicting All 67 Characters
63. Captain America
As I've argued recently, contrary to fan expectation Steve Rogers is probably going to make it through Civil War alive (and if he doesn't, it's not like death is permanent in Marvel movies), putting him in a prime position to play a key role in Infinity War. Chris Evans is contracted for at least one more Avengers movie too, so it's the most obvious-not-obvious inclusion (although don't bet on him being around for much longer after that).
62. Bucky Barnes
With Sebastian Stan only three movies into a nine-movie contract, the former Winter Soldier is a lock to appear here. Heck, he could suddenly become a very important character if his childhood friend bites it at some point in Infinity War (although even if not he's definitely going to take up that shield eventually).
61. Falcon
Sam Wilson became a fully-fledged member of The Avengers at the end of Age Of Ultron, and with all the talk of a new team going forward, it's likely Anthony Mackie will wind up being an even bigger part of the series. Quite what sort of role he'll play here will really depend on what the status quo of Earth's Mightiest Heroes is at the end of Civil War though.
60. Red Skull
OK, I'm going out on a limb here, but Red Skull has to return eventually. He's not only a highly prolific villain from the comics ripe for exploration outside of what we got in Captain America: The First Avenger, but his "death" was incredibly ambiguous - he appeared to be transported across space by the Tesseract. As Thanos will be wanting that Infinity Stone for his Gauntlet, it's within possibility he'll be able to resurrect/rescue the Hydra chief for his own ends (although probably not played by Hugo Weaving).