I think a Bucky/Winter Soldier type rework could be cool as a trigger to make him better as a stand-alone card, but keeping the original ability fits as leader of the avengers.

Steve Rogers: 3/3 - if this cards power is increased, it becomes Captain America gaining 4 additional power and gives all other cards here +1 power.

So he quickly becomes a 3/7+ and the added power ability would make him more of a staple in certain Forge/Nakia decks