I heard the same thing. When Blizzard said they'd move the Outland to the caverns of time "because the Outland campaign is in the past anyway", I thought it was sensible.I've heard they said you'd start in Tanaan Jungle, do only a few introduction quests and you'll be sent to your faction's starting zone. Not sure if that's still correct, but I don't think you start right off in Frostfire Ridge or Shadowmoon Valley.
Having Khadgar coming with us could just mean that we fight through the portal and help him to blow it up on the other side, then its off to our starting zone to gather allies and fight back against this Iron Horde while they struggle to rebuild the thing after we flattened it.
The Khar revamp could be us meeting with Khadgar, fetching knowledge hidden in Medivh's journals or some super powerful artifact to help us close the portal on our suicide mission.