The Account Inventory will now only house account bound items (Items that already exist in your Account Inventory will keep their previous functionality until they are all claimed down).
Does this mean that if you, for example, bought a pack of 3 lockbox keys, they'd all get sent to the character currently being played? Because that's not a good idea. I often buy things like that and spread them out among my characters as needed. For example if I got a C.A.T. on my main and still had keys left, I would probably want to use the remaining keys on a different character, possibly one on the opposite faction.
Similarly, I pick up login rewards on the first character I log in to, but if it's a soulbound item I may want it on a different character and prefer to leave it in account inventory. Especially XP flasks.
I'm not able to check right now, if I could I'd find out myself instead of asking.