Included in Ashran will be faction bases (that can be reduced to rubble) and other hotspots. You'll be able to create siege vehicles of various sizes that may be started at one point and finished when you return to the zone. Ashran is being described as being close to the old school Alterac Valley. There will be a variety of objectives that may take a lot of time to achieve. Also, cross-realm technology will be applied so that servers or server clusters with faction-imbalances will have fair battles.
This is a departure from their current PvP options in that there is no end. Fans of the old AV and of world PvP will hopefully find that Ashran satisfies those desires.