When you deactivate all platforms go back to only being able to access their own save data, in your case your Playstation would retain the characters/gear etc as its your active profile for cross-save and any (/ all) progress made while playing on Xbox has been made on your Playstation Destiny account. Your Xbox would go back to whatever it had before cross-save was enabled, if anything existed on it. The /invite and /join codes would also not function properly for any accounts besides the Xbox account due to how Destiny handles look ups. There isn't a way to permanently transfer your PS destiny data (characters, gear etc) to the Xbox account, cross-save is as close as it gets but the info is always going to be tied to the PS account.