[BullMcGiveny]

I would say that Winter Soldier will be the main villain, but answerable to Zemo/Lukin/???, who will be the true villain, but with less screentime.

In other words, Lukin/Zemo will be Palpitine, and Winter Soldier will be Vader. Similarly, I imagine Bucky's deprogramming happening fairly late in the movie.

Crossbones will be another Lukin/Zemo henchman, possibly his top henchman, but still 'below' Bucky.