So, the Sitwell interrogation. So far more famously known for acknowledging the existence of Doctor Strange. But he also made mention of "an honour student in Iowa" who is a threat to HYDRA. Who is this student?
Well, after a little digging I have figured out who it is.
It's Nomad.
Jack Munroe, the only character from Iowa in the Marvel universe with any relation to Captain America. The only other character from Iowa is a Skrull.
But what threat would he pose to HYDRA? Well, he’s taken a different type of the super soldier serum (thanks to Red Skull) and also has relations to Grand Director. Also known as William Burnside, who later legally changed his name to “Steven Rogers”, is a character already made mention by the Russo brothers who have said they would like to use him in Captain America 3 as a possible villain.
Nomad and Grand Director were also Bucky and Captain America, respectively, during the 50’s to keep Captain America’s name going long after WWII had ended.
My guess to why HYDRA are interested in, supposedly, Jack Munroe is because of his recreation with William of the super soldier serum and HYDRA want a hold of this serum.
So as well as making mention of Doctor Strange we get mention of Nomad and a possible story emerging already for Captain America 3. I'm sure you can put the pieces together to see what could happen.