For obvious reasosn already cast characters will not be changed, even though I wish we could replace Scarlet as Black Widow.
I am going to include the characters I would most like to see join the Avengers. Seeing as Thanos appears to be being set as the villain, I will not fancast a villainous character.
Ant Man - Aaron Eckhart
This was an easy choice. For the character I wanted someone in an age range right around RDJ and Ruffalo. More than likely a fair amount of science or intelligence based scenes will take place in the sequel and Eckhart is a strong enough actor to hold his own amongst outstanding actors like RDJ and Ruffalo, while also having a charm and charisma that could help him stand out rather than fall to background status and could command the lead role in an Ant Man movie.
Ant Man
Aaron Eckhart
Wasp - Emmy Rossum
Wasp was a difficult decision to make. Most fancasts go with Morena Baccarin; and as much as I like her, I feel her inclusion tended to be more due to her connection with Nathan Fillion rather than ability to pull off the role.
I chose Emmy Rossum because she is an extremely gorgeous woman and a very talented actress. Her look can be very sexy, yet she also has a look that to me says, there is more than just looks with her which is necessary for the character.
Wasp
Emmy Rossum
Black Panther - Chiwetel Ejiofor
Chiwetal is one of the most underrated actors around. He has the all the abilities, talent and look to be a badass Black Panther
Black Panther
Chiwetel Ejiofor
The Falcon - Anthony Mackie
Now I know the popular choice of late is Jamie Foxx. While I agree he would kill it as The Falcon, I think his star power outshines that of Chris Evans as Cap, and seeing as Cap is the star and Falcon basically a sidekick, it really makes no sense to have a bigger name for a sidekick than the headliner. Mackie is a good up and coming actor, and would definitely be able to pull off the role.
Falcon
Anthony Mackie
Namor - Ian Somerhalder
For me, Namor was a difficult decision. After racking my brain for the perfect fit, it came to me that other fancasts were right with this selection. Somerhalder is a strong actor and has the perfect look for Namor.
Namor
Ian Somerhalder
Ms Marvel - Yvonne Strahovski
This was a no brainer. Beatiful, sexy, good actress, and looks good kicking ass. If you don't believe me or numerous others who have cast her, than try and watch Chuck.
Ms Marvel
Yvonne Strahovski