POTENTIAL SPOILERS!
As Marvel Comics fans may know, Thunderbolt Ross IS The Red Hulk. In the comics, he blamed The Hulk for the death of his daughter, Betty. The Leader (along with MODOK and Doc Samson) turned Ross into The Red Hulk so he could seek revenge.
It’s also possibly why the MCU Ross shaved his mustache. In the comics, Ross’s mustache somehow disappeared when he became Red Hulk, which was probably just a way to keep his identity a surprise. That tactic might not work for a mainstream film audience, so a clean-shaven Ross might be a simple solution.
Plus, for what it’s worth, who was the last US President to have a mustache? William Howard Taft 111 years ago!
While they are not physically seen in the trailer, Liv Tyler and Tim Blake Nelson reprise their respective roles of Betty Ross and The Leader. They were last seen in 2008’s The Incredible Hulk. We do hear The Leader from behind making threats and giving orders to unknown people.
The funeral we see may be for Betty, which would certainly explain Ross’s need for revenge. Hence where The Leader comes in.
We don’t know how Giancarlo Esposito’s character fits in, other than he is likely a villain. Is he responsible for Betty’s death, if she dies in the movie? Or could The President himself be in league with these potential terrorists?
We’ll surely get more trailers in the future since the film is over six months away from release.