Lining up the entire 1-60 questing experience with current lore would take a significant time investment that Blizz has said they aren't likely to do. The Cata revamp took a lot of time/resources away from other content and had little value once you leveled through. Going through and removing quests that deal with Garrosh would be difficult and require a total revamp of some zones (Ashenvale/Stonetalon/kinda silverpine etc etc). It'll prob just be turned in to a phased version of him or another random NPC.
That being said, if it were up to me I'd burn the whole quest chain down and have Brutusk piss on the ashes.
I agree and disagree with this. I think they would revamp the city (again) if its expansion worthy, they would most likely leave the zone stuff with garrosh still in though. I cant see them phasing an entire city like that, unless maybe its just the throne room for a new warchief. Although i havent played 5.2 much, i hear they made Dalaran alliance only? So maybe it is possible. Anyhow, interesting stuff ahead. Expect 5.4 to be a massive patch!