I also think Sadie, Charles Smith and Micah will be extremely important as well. I still think Charles will be some what of a catalyst that makes Dutch start to take up the plight for Native AmericansDutch is the second character lead, so he's more important to the story and the gang compare to John.
John's more important to the player cause he was the protagonist in the previous title. Going into RDR2 we have more emotion attachment to John than anyone else.