Id be annoyed if I lose all of the shit I got while as Arthur. I love John though so it wouldn't like destroy me as of right now, and as long as Arthur's departure doesn't upset me/make me super sad.
Nah, Arthur tells John to run away/escape the gang with his family and dies trying to stop Dutch. Pretty much spelled out for you in the first (announcement) trailer
Do not bump threads for no reason. If you want to discuss Open spoilers for RDR 2, you can make a Spoiler Specific Thread for it such as "Red Dead Redemption 2 - Open Spoiler Discussion".