Captain America being Falcon is good. It seems natural and already set up. I kinda hope they keep the name Falcon, but I will respect that. Iron Heart needs to be done, but I just hope they give it time first. Let the newish old Avengers have a Limelight for awhile. I mean we are going to get a New Black Widow probably (I am excited) A New Hawkeye, A She-Hulk. So that is 4 of the original Avengers having new incarnations. We will see what happens with Thor 4, but I don't think we will have Jane Foster as Thor for very long. So I am not going to say she is the default new version of Thor.
I think if they introduce Iron Heart, a cool movie plot would be War Machine vs. Iron Man...and have James Rhodes be a Iron Man-sized War Machine...with Iron Man colors and everything, and see the suit used in more military like patriotic missions, a puppet of the US military...and then Riri Williams comes with her Iron Man and reminds James what it is like to be a hero fighting for everyone, not just the government.