Jacobs also touched on other topics, including crafting and the absence of PvE. Players who want to both fight and craft extensively will need to rely on alts. as fighters will have limited crafting options. And don't think the world will be empty just because there will be no traditional PvE; Jacobs assured that there will be NPCs, noting "You can skin them, get materials off them, salvage their weapons, armor, etc. but you cannot level your RvR skills by doing that."
[Thanks to Mikkel for the tip!]